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Diagnosis and management of an endometrial cancer patient with Cowden syndrome

  • Beryl L. Manning-Geist
    Affiliations
    Gynecology Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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  • Sonia Gatius
    Affiliations
    Pathology and Medical Oncology Departments, Hospital Universitari Arnau de Vilanova, IRBLLEIDA, CIBERONC, University of Lleida, Lleida, Spain
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  • Ying Liu
    Affiliations
    Gynecologic Medical Oncology, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA

    Clinical Genetics Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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  • Mabel Gil
    Affiliations
    Radiology Department, Institut de Diagnòstic per la Imatge / Hospital Universitari Arnau de Vilanova, IRBLLEIDA, University of Lleida, Lleida, Spain
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  • Arnaud Da Cruz Paula
    Affiliations
    Gynecology Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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  • Noemi Tuset
    Affiliations
    Pathology and Medical Oncology Departments, Hospital Universitari Arnau de Vilanova, IRBLLEIDA, CIBERONC, University of Lleida, Lleida, Spain
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  • Nadeem R. Abu-Rustum
    Affiliations
    Gynecology Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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  • Carol Aghajanian
    Affiliations
    Gynecologic Medical Oncology, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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  • Author Footnotes
    1 Co-senior authors.
    Britta Weigelt
    Correspondence
    Correspondence to: B. Weigelt, Department of Pathology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
    Footnotes
    1 Co-senior authors.
    Affiliations
    Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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  • Author Footnotes
    1 Co-senior authors.
    Xavier Matias-Guiu
    Correspondence
    Correspondence to: X. Matias-Guiu, Hospital Universitari de Bellvitge, IDIBELL, and Hospital Universitari Arnau de Vilanova, IRBLLEIDA, Universities of Lleida and Barcelona, CIBERONC, Spain.
    Footnotes
    1 Co-senior authors.
    Affiliations
    Pathology and Medical Oncology Departments, Hospital Universitari Arnau de Vilanova, IRBLLEIDA, CIBERONC, University of Lleida, Lleida, Spain

    Pathology Department, Hospital Universitaride Bellvitge, IDIBELL, University of Barcelona, Barcelona, Spain
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  • Author Footnotes
    1 Co-senior authors.
Published:August 23, 2021DOI:https://doi.org/10.1016/j.ygyno.2021.08.008

      Abstract

      Somatic PTEN alterations are common in endometrial carcinoma (EC), but in rare cases PTEN mutations are associated with inherited syndromes. Here, we present a case of Cowden syndrome-associated EC. We discuss clinical, pathologic and molecular features of her tumor and PTEN-mutated EC, inherited syndromes predisposing to EC and PTEN-targeted therapies.

      Keywords

      1. Presentation of case

      A 39-year-old patient presented with 6 months of polymenorrhea and abdominal pain. Her medical history was unremarkable, however she reported a family history of renal clear cell carcinoma diagnosed in her father at age 50. Pelvic examination was notable for three 1 cm friable polypoid lesions that protruded through the external cervical os, and a polypectomy was performed. Pathologic examination revealed infiltration of the polyp by an endometrioid-type adenocarcinoma. The patient underwent transvaginal ultrasound and hysteroscopy, which demonstrated an endometrial cavity with multifocal exophytic lesions. Targeted sampling revealed a FIGO grade 1 endometrioid carcinoma with squamous differentiation. Subsequently, contrast-enhanced magnetic resonance imaging (MRI) showed an endometrial tumor with cervical extension and deep myometrial invasion as well as a left ovarian mass (Fig. 1). The patient underwent total abdominal hysterectomy, bilateral salpingoophorectomy, appendectomy, omentectomy, mesenteric implant resection, and bilateral pelvic and paraaortic lymphadenectomy. Histologic assessment of the surgical specimen rendered a diagnosis of a grade 1 stage IIIC (FIGO 2009) endometrioid endometrial carcinoma (EC) with left ovarian and pelvic lymph node metastases. The tumor was mismatch repair (MMR) proficient by immunohistochemistry (IHC). Following surgery, the patient was treated with four cycles of carboplatin and paclitaxel. Interval imaging demonstrated persistence of retroperitoneal and pelvic lymphadenopathy, and the patient was transitioned to external beam radiation therapy (EBRT; 4680 cGy) and weekly paclitaxel for 6 cycles following the institutional standard of care at that time, and achieved complete remission.
      Fig. 1
      Fig. 1Pre-therapy imaging studies of the abdomen and pelvis.
      A, Axial T2 weighted magnetic resonance (MR) image shows endometrial tumor with extension into the cervix (white arrow) and heterogeneous left ovarian mass with solid and cystic components (black arrow). B, Sagittal T1 weighted sagittal MR image demonstrates deep myometrial invasion (black arrow): the endometrial tumor is hypointense relative to the hyperintense enhancing myometrium with invasion of the outer half of the myometrium.
      A few months later, a suspicious left breast lesion was detected on computerized tomography (CT) surveillance. A core biopsy demonstrated a low-grade invasive ductal carcinoma, and lumpectomy and sentinel lymph node dissection were performed. The patient was staged as pT2pN1mi(mol+), and the invasive breast cancer was estrogen receptor (ER)-positive/ progesterone receptor (PR)-negative/ HER2-negative and had an Oncotype DX recurrence score of 24. The patient was treated with hypofractionated axillary radiation at a dose of 40.05 Gy followed by a 9 Gy boost and hormonal therapy (tamoxifen, followed by leuprorelin and exemestane), and she achieved complete remission.
      In the setting of her multiple cancer diagnoses at age 39, the patient was referred to genetic counseling. Lynch syndrome was ruled out given the absence of microsatellite instability in the EC and the retained MMR protein expression in both endometrial and breast tumors. Physical examination revealed macrocephaly as well as multiple skin lesions consistent with trichilemmoma (hamartomas of the hair follicle). Germline testing demonstrated a p.Q110fs*5 frameshift mutation in the phosphatase and tensin (PTEN) gene, and a diagnosis of Cowden syndrome (CS) was rendered.

      2. Pathology review of the endometrial and breast lesions

      Pathologic evaluation of the patient's endometrial tumor revealed a low-grade EC with bilateral ovarian metastases and pelvic lymph node involvement (previously reported in [
      • Schultheis A.M.
      • Ng C.K.
      • De Filippo M.R.
      • Piscuoglio S.
      • Macedo G.S.
      • Gatius S.
      • et al.
      Massively parallel sequencing-based clonality analysis of synchronous endometrioid endometrial and ovarian carcinomas.
      ]). The uterus contained a large irregular mass of gray-white tissue, 4 cm in largest diameter, which protruded into the endometrial cavity (Fig. 2A ) [
      • WHO Classification of Tumours Editorial Board
      Female Genital Tumours.
      ]. It was composed of tubular glands with irregular and angulated profiles (Fig. 2B). Marked complexity with fusion of the glands and cribriform masses was also seen. Squamous and morular differentiation was observed across the tumor. Tumor architecture was predominantly glandular and corresponded to FIGO grade 1 disease (Fig. 2B). The tumor was associated with more than 50% myometrial invasion as well as cervical stromal invasion. Extensive lymphovascular space invasion was seen, with more than 5 vessels with tumor emboli. The histologic features of the ovarian and pelvic lymph node metastases were similar [
      • Schultheis A.M.
      • Ng C.K.
      • De Filippo M.R.
      • Piscuoglio S.
      • Macedo G.S.
      • Gatius S.
      • et al.
      Massively parallel sequencing-based clonality analysis of synchronous endometrioid endometrial and ovarian carcinomas.
      ]. By IHC, tumor cells were strongly ER-positive, and wild-type p53 expression and retained expression of the MMR proteins MLH1, MSH2, MSH6 and PMS2 was observed.
      Fig. 2
      Fig. 2Pathology of the endometrial carcinoma.
      A, Gross appearance of the uterus showing a 4 cm mass protruding into endometrial cavity (right) and ovarian metastasis (left). Reprinted from WHO Classification of Tumours Editorial Board. Female Genital Tumours. Lyon (France), IARC 2020 [
      • WHO Classification of Tumours Editorial Board
      Female Genital Tumours.
      ]. B, Representative hematoxylin and eosin-stained section showing a grade 1 endometrioid endometrial carcinoma with complex cribriform glands and marked squamous and morular differentiation (20×). C, PTEN immunohistochemical expression of endometrial carcinoma (DAB 20×; Clone 6H2,1; Agilent/Dako). Tumor cells show loss of expression of PTEN in the presence of internal controls. Scale bars, A, 100 μm, B, 50 μm.
      The invasive ductal carcinoma not otherwise specified (NOS) of the breast (SBR differentiation grade I, MSBR nuclear grade II) was ER-positive/HER2-negative and had a low Ki-67 index. PTEN IHC was performed in both the endometrial and breast lesions, which revealed lack of PTEN expression in the tumor cells in the presence of a positive internal stromal control (Fig. 2C). Sanger sequencing analysis of normal tissue-derived DNA demonstrated the presence of a PTEN p.Q110fs*5 germline mutation.

      3. Pathology of PTEN mutations

      PTEN plays an important role in the early stages of endometrial tumorigenesis. Until recently, there was lack of well-validated antibodies to reliably detect and interpret PTEN loss by IHC [
      • Pallares J.
      • Bussaglia E.
      • Martinez-Guitarte J.L.
      • Dolcet X.
      • Llobet D.
      • Rue M.
      • et al.
      Immunohistochemical analysis of PTEN in endometrial carcinoma: a tissue microarray study with a comparison of four commercial antibodies in correlation with molecular abnormalities.
      ], however PTEN IHC analysis has since improved and is now considered a reliable surrogate marker for PTEN mutations [
      • Maiques O.
      • Santacana M.
      • Valls J.
      • Pallares J.
      • Mirantes C.
      • Gatius S.
      • et al.
      Optimal protocol for PTEN immunostaining; role of analytical and preanalytical variables in PTEN staining in normal and neoplastic endometrial, breast, and prostatic tissues.
      ].
      PTEN mutations are occasionally detected in normal endometrial cells in premenopausal women by lack of PTEN expression by IHC [
      • Lac V.
      • Nazeran T.M.
      • Tessier-Cloutier B.
      • Aguirre-Hernandez R.
      • Albert A.
      • Lum A.
      • et al.
      Oncogenic mutations in histologically normal endometrium: the new normal?.
      ]. It is thought that, in the absence of estrogenic excess, these glands are shed during menses. When a patient is under estrogen stimulation as in the setting of obesity, PTEN-null glands may overgrow and give rise to endometrial hyperplasia, endometrioid intraepithelial neoplasia, and ultimately, endometrioid EC. In fact, identical PTEN mutations have been detected in hyperplasias preceding or coexisting with EC [
      • Bussaglia E.
      • del Rio E.
      • Matias-Guiu X.
      • Prat J.
      PTEN mutations in endometrial carcinomas: a molecular and clinicopathologic analysis of 38 cases.
      ]. The role of PTEN in endometrial tumorigenesis is also reflected by the increased frequency of EC in patients with germline PTEN mutations.
      There is a paucity of data on the pathologic features of ECs arising in patients with CS. In a review of 371 prospectively enrolled patients with CS and Cowden-like syndrome and EC, endometrioid carcinoma was the predominant histologic subtype [
      • Mahdi H.
      • Mester J.L.
      • Nizialek E.A.
      • Ngeow J.
      • Michener C.
      • Eng C.
      Germline PTEN, SDHB-D, and KLLN alterations in endometrial cancer patients with Cowden and Cowden-like syndromes: an international, multicenter, prospective study.
      ]. Other studies have reported that EC occurs at earlier age in CS in comparison with other hereditary syndromes with predisposition to EC, and retrospective studies have shown that EC diagnoses occur before age 50 in up to 40% of CS patients [
      • Mahdi H.
      • Mester J.L.
      • Nizialek E.A.
      • Ngeow J.
      • Michener C.
      • Eng C.
      Germline PTEN, SDHB-D, and KLLN alterations in endometrial cancer patients with Cowden and Cowden-like syndromes: an international, multicenter, prospective study.
      ,
      • Ring K.L.
      • Bruegl A.S.
      • Allen B.A.
      • Elkin E.P.
      • Singh N.
      • Hartman A.R.
      • et al.
      Germline multi-gene hereditary cancer panel testing in an unselected endometrial cancer cohort.
      ]. In summary, early age of presentation, clinical setting, endometrioid morphology, and lack of PTEN expression by IHC may provide useful clues in diagnosing a patient with CS.

      4. Inherited syndromes predisposing to EC

      Although many environmental risk factors for EC have been identified, an inherited predisposition is thought to be present in about 5% of women with this disease [
      • Ryan N.A.J.
      • Glaire M.A.
      • Blake D.
      • Cabrera-Dandy M.
      • Evans D.G.
      • Crosbie E.J.
      The proportion of endometrial cancers associated with lynch syndrome: a systematic review of the literature and meta-analysis.
      ,
      • Cadoo K.A.
      • Mandelker D.L.
      • Mukherjee S.
      • Stewart C.
      • DeLair D.
      • Ravichandran V.
      • et al.
      Understanding inherited risk in unselected newly diagnosed patients with endometrial cancer.
      ]. The most common inherited syndrome in EC is Lynch syndrome, which is associated with MMR-deficient (MMRd)/microsatellite instability-high (MSI-H) tumors, as well as colon cancers and other cancers exhibiting an MMRd/MSI-H phenotype [
      • Dominguez-Valentin M.
      • Sampson J.R.
      • Seppala T.T.
      • Ten Broeke S.W.
      • Plazzer J.P.
      • Nakken S.
      • et al.
      Cancer risks by gene, age, and gender in 6350 carriers of pathogenic mismatch repair variants: findings from the prospective lynch syndrome database.
      ]. As a result, universal MMR/MSI testing is recommended in EC to identify patients for Lynch syndrome testing and subsequent cancer prevention [
      • National Comprehensive Cancer Network (NCCN)
      Genetic/Familial High-Risk Assessment: Breast, Ovarian and Pancreatic.
      ]. In a small subset of EC patients, germline mutations in CHEK2, POLD1/POLE, MUTYH, and other genes involved in DNA repair have been identified [
      • Ring K.L.
      • Bruegl A.S.
      • Allen B.A.
      • Elkin E.P.
      • Singh N.
      • Hartman A.R.
      • et al.
      Germline multi-gene hereditary cancer panel testing in an unselected endometrial cancer cohort.
      ,
      • Cadoo K.A.
      • Mandelker D.L.
      • Mukherjee S.
      • Stewart C.
      • DeLair D.
      • Ravichandran V.
      • et al.
      Understanding inherited risk in unselected newly diagnosed patients with endometrial cancer.
      ,
      • Smith E.S.
      • Da Cruz Paula A.
      • Cadoo K.A.
      • Abu-Rustum N.R.
      • Pei X.
      • Brown D.N.
      • et al.
      Endometrial cancers in BRCA1 or BRCA2 germline mutation carriers: assessment of homologous recombination DNA repair defects.
      ]. There are burgeoning data to suggest a mildly increased risk of serous-like EC, endometrioid EC, and p53-abnormal EC in those with germline BRCA1 mutations as well as an increased risk of serous-like EC in germline BRCA2 mutations when compared with expected incidence rates, although absolute risk by age 75 remains low (3.0%) for the germline BRCA1/2 population [
      • de Jonge M.M.
      • de Kroon C.D.
      • Jenner D.J.
      • Oosting J.
      • de Hullu J.A.
      • Mourits M.J.E.
      • et al.
      Endometrial cancer risk in women with germline BRCA1 or BRCA2 mutations: multicenter cohort study.
      ]. While less common, germline alterations in PTEN also represent an important contributor to germline EC risk.

      5. Characteristics of CS and germline PTEN mutations

      CS is an autosomal dominant condition arising from germline mutations in the PTEN gene that is associated with increased cancer risk, including EC [
      • Pilarski R.
      • Eng C.
      Will the real Cowden syndrome please stand up (again)? Expanding mutational and clinical spectra of the PTEN hamartoma tumour syndrome.
      ]. PTEN, located on chromosome 10q23.31, encodes a tumor suppressor protein that regulates the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway via dephosphorylation of phosphatidylinositol-3,4,5-triphosphate (PIP3) [
      • Zhang S.
      • Yu D.
      PI(3)king apart PTEN’s role in cancer.
      ]. Somatic mutations in PTEN have been found in many tumor types, including brain, skin and prostate, and it is one of the most commonly altered genes in EC [
      • Zhang S.
      • Yu D.
      PI(3)king apart PTEN’s role in cancer.
      ,
      • Kong D.
      • Suzuki A.
      • Zou T.T.
      • Sakurada A.
      • Kemp L.W.
      • Wakatsuki S.
      • et al.
      PTEN1 is frequently mutated in primary endometrial carcinomas.
      ].
      Heterozygous germline mutations in PTEN are associated with the PTEN hamartoma tumor syndrome (PHTS), which includes CS, Bannayan-Riley-Ruvalcaba syndrome (BRRS), PTEN-related Proteus syndrome (PS), and PTEN-related Proteus-like syndrome [
      • Pilarski R.
      • Eng C.
      Will the real Cowden syndrome please stand up (again)? Expanding mutational and clinical spectra of the PTEN hamartoma tumour syndrome.
      ,
      • Nelen M.R.
      • Padberg G.W.
      • Peeters E.A.
      • Lin A.Y.
      • van den Helm B.
      • Frants R.R.
      • et al.
      Localization of the gene for Cowden disease to chromosome 10q22-23.
      ]. CS is estimated to affect 1 in 200,000 individuals, with penetrance related to age. Most CS patients present with mucocutaneous lesions by their late twenties, however the clinical presentation can be variable and subtle, leading to potential under-diagnosis [
      • Pilarski R.
      • Eng C.
      Will the real Cowden syndrome please stand up (again)? Expanding mutational and clinical spectra of the PTEN hamartoma tumour syndrome.
      ,
      • Pilarski R.
      Cowden syndrome: a critical review of the clinical literature.
      ]. Additionally, germline mutations in succinate dehydrogenase genes as well as promoter methylation of KILLIN, a gene upstream of PTEN with the same transcriptional start site but opposite direction, have also been found in patients with clinical features of CS but without germline PTEN mutations [
      • Mahdi H.
      • Mester J.L.
      • Nizialek E.A.
      • Ngeow J.
      • Michener C.
      • Eng C.
      Germline PTEN, SDHB-D, and KLLN alterations in endometrial cancer patients with Cowden and Cowden-like syndromes: an international, multicenter, prospective study.
      ,
      • Bennett K.L.
      • Mester J.
      • Eng C.
      Germline epigenetic regulation of KILLIN in Cowden and Cowden-like syndrome.
      ].
      To aid in diagnosis, the National Comprehensive Cancer Network (NCCN) has modified the original consortium clinical criteria to include family history as well as major/minor criteria [
      • National Comprehensive Cancer Network (NCCN)
      Genetic/Familial High-Risk Assessment: Breast, Ovarian and Pancreatic.
      ]. The major criteria include breast cancer, thyroid cancer (follicular type), macrocephaly (≥97th percentile), Lhermitte-Duclos disease (presence of a cerebellar dysplastic gangliocytoma), gastrointestinal hamartomas or ganglioneuromas, macular pigmentation of glans penis, mucocutaneous lesions such as one biopsy-proven trichilemmoma, multiple palmoplantar keratoses, multifocal or extensive oral mucosal papillomatosis, or multiple cutaneous facial papules, and EC. Minor criteria include autism spectrum disorder, colon cancer, esophageal glycogenic acanthoses (≥3), lipomas (≥3), intellectual disability (IQ ≤ 75), renal cell carcinoma, papillary thyroid cancer, benign thyroid lesions (adenomas, multinodular goiter), testicular lipomatosis, or vascular anomalies [
      • National Comprehensive Cancer Network (NCCN)
      Genetic/Familial High-Risk Assessment: Breast, Ovarian and Pancreatic.
      ,
      • Pilarski R.
      • Eng C.
      Will the real Cowden syndrome please stand up (again)? Expanding mutational and clinical spectra of the PTEN hamartoma tumour syndrome.
      ,
      • Pilarski R.
      Cowden syndrome: a critical review of the clinical literature.
      ]. A diagnosis of CS is assigned if three major criteria (with at least one including macrocephaly, Lhermitte-Duclos disease, or GI hamartomas) or two major and three minor criteria are present. Diagnosis in the setting of a family history of CS is assigned if any two major criteria, one major and two minor criteria, or three minor criteria are present. Given the heterogeneity and concerns for under-diagnosis, the Cleveland Clinic score was also developed from a prospective cohort of 3042 probands as a risk calculator tool for estimating probability of germline PTEN mutations in adult patients without a family history. This showed high sensitivity in identifying patients with germline PTEN mutations [
      • Tan M.H.
      • Mester J.
      • Peterson C.
      • Yang Y.
      • Chen J.L.
      • Rybicki L.A.
      • et al.
      A clinical scoring system for selection of patients for PTEN mutation testing is proposed on the basis of a prospective study of 3042 probands.
      ].
      CS is associated with an increased lifetime risk of cancer (~85%), particularly breast, thyroid, endometrial, colon, melanoma and kidney cancers [
      • Pilarski R.
      Cowden syndrome: a critical review of the clinical literature.
      ,
      • Tan M.H.
      • Mester J.L.
      • Ngeow J.
      • Rybicki L.A.
      • Orloff M.S.
      • Eng C.
      Lifetime cancer risks in individuals with germline PTEN mutations.
      ]. The estimated lifetime risk of breast cancer ranges from 35 to 50% in older studies [
      • Pilarski R.
      Cowden syndrome: a critical review of the clinical literature.
      ] and up to 80–90% in more recent studies [
      • Tan M.H.
      • Mester J.L.
      • Ngeow J.
      • Rybicki L.A.
      • Orloff M.S.
      • Eng C.
      Lifetime cancer risks in individuals with germline PTEN mutations.
      ], with average age of diagnosis ranging from late 30's to early 40's [
      • Pilarski R.
      Cowden syndrome: a critical review of the clinical literature.
      ]. Estimated lifetime risk of follicular or papillary thyroid cancer is 10–30%, whereas medullary thyroid cancers are not felt to be a part of CS [
      • Pilarski R.
      Cowden syndrome: a critical review of the clinical literature.
      ,
      • Tan M.H.
      • Mester J.L.
      • Ngeow J.
      • Rybicki L.A.
      • Orloff M.S.
      • Eng C.
      Lifetime cancer risks in individuals with germline PTEN mutations.
      ]. The estimated lifetime risk of EC ranges from 5 to 30% [
      • Pilarski R.
      Cowden syndrome: a critical review of the clinical literature.
      ,
      • Tan M.H.
      • Mester J.L.
      • Ngeow J.
      • Rybicki L.A.
      • Orloff M.S.
      • Eng C.
      Lifetime cancer risks in individuals with germline PTEN mutations.
      ]. More recent studies have also revealed an increased risk of renal cell carcinoma (~30% lifetime risk), colorectal cancer (~10% lifetime risk) and melanoma (~5–10% lifetime risk) [
      • Tan M.H.
      • Mester J.L.
      • Ngeow J.
      • Rybicki L.A.
      • Orloff M.S.
      • Eng C.
      Lifetime cancer risks in individuals with germline PTEN mutations.
      ]. Uterine fibroids, ovarian cysts and other benign gynecologic findings may also be common, although exact incidence is unknown [
      • Tan M.H.
      • Mester J.L.
      • Ngeow J.
      • Rybicki L.A.
      • Orloff M.S.
      • Eng C.
      Lifetime cancer risks in individuals with germline PTEN mutations.
      ].
      Recommendations for management of increased cancer risk in CS vary. Given the elevated risk of breast cancer, the NCCN recommends self-exams and education beginning at age 18, a clinical breast exam every 6–12 months starting at age 25, and annual mammography and breast MRI starting at age 30–35 or 5–10 years before the earliest known breast cancer in the family (whichever comes first). Risk-reducing bilateral mastectomy can be considered on an individual basis. Recommendations also include annual thyroid ultrasound starting at age 7, annual dermatologic exams, and colonoscopy every 5 years, or more frequently if symptomatic or polyps are identified, from age 35 or 5–10 years before the earliest known colon cancer in the family (whichever comes first). Consideration of renal imaging every 1–2 years beginning at age 40 is also recommended. Screening for EC is more controversial as it has not been shown to reduce mortality, however additional imaging, endometrial biopsy, or risk-reducing hysterectomy after completion of child-bearing may be considered on an individual basis [
      • National Comprehensive Cancer Network (NCCN)
      Genetic/Familial High-Risk Assessment: Breast, Ovarian and Pancreatic.
      ].
      Although EC has been recognized as a key component of CS, its prevalence and clinical features are not well characterized. A study evaluating EC patients with CS or CS-like clinical picture (more relaxed criteria than those of NCCN) found germline PTEN mutations in 7% of patients, germline SDHX mutations in 9.8%, and KILLIN promoter hypermethylation in 10.5% of patients [
      • Mahdi H.
      • Mester J.L.
      • Nizialek E.A.
      • Ngeow J.
      • Michener C.
      • Eng C.
      Germline PTEN, SDHB-D, and KLLN alterations in endometrial cancer patients with Cowden and Cowden-like syndromes: an international, multicenter, prospective study.
      ]. Although associations with specific genomic characteristics are unknown, CS was more likely to be present in those with EC and age at diagnosis <50, macrocephaly, and concurrent renal cell carcinoma [
      • Mahdi H.
      • Mester J.L.
      • Nizialek E.A.
      • Ngeow J.
      • Michener C.
      • Eng C.
      Germline PTEN, SDHB-D, and KLLN alterations in endometrial cancer patients with Cowden and Cowden-like syndromes: an international, multicenter, prospective study.
      ]. This study and others highlight the low yield of germline testing in unselected EC patients [
      • Cadoo K.A.
      • Mandelker D.L.
      • Mukherjee S.
      • Stewart C.
      • DeLair D.
      • Ravichandran V.
      • et al.
      Understanding inherited risk in unselected newly diagnosed patients with endometrial cancer.
      ], however certain clinical features such as those seen in this patient, including younger age of diagnosis, macrocephaly, and concurrent cancers, may warrant germline assessment.

      6. Molecular features and mutational signatures analysis of PTEN-mutant ECs

      PTEN is one of the most recurrently altered genes in EC, with approximately 55–65% of unselected sporadic ECs harboring a somatic PTEN mutation, primarily in the form of truncating or missense mutations [
      • The Cancer Genome Atlas Research Network
      • Kandoth C.
      • Schultz N.
      • Cherniack A.D.
      • Akbani R.
      • Liu Y.
      • et al.
      Integrated genomic characterization of endometrial carcinoma.
      ]. In The Cancer Genome Atlas (TCGA) EC study, PTEN was found to be altered in the majority (>75%) of ECs of POLE, MSI hypermutated or copy-number low (CN-L) molecular subtype, however it was rarely altered (<10%) in copy-number high (CN-H) ECs [
      • The Cancer Genome Atlas Research Network
      • Kandoth C.
      • Schultz N.
      • Cherniack A.D.
      • Akbani R.
      • Liu Y.
      • et al.
      Integrated genomic characterization of endometrial carcinoma.
      ]. In addition, somatic PTEN mutations often co-occur with other alterations in the PI3K pathway, including PIK3CA, PIK3R1 and/or KRAS mutations [
      • The Cancer Genome Atlas Research Network
      • Kandoth C.
      • Schultz N.
      • Cherniack A.D.
      • Akbani R.
      • Liu Y.
      • et al.
      Integrated genomic characterization of endometrial carcinoma.
      ,
      • Urick M.E.
      • Rudd M.L.
      • Godwin A.K.
      • Sgroi D.
      • Merino M.
      • Bell D.W.
      PIK3R1 (p85alpha) is somatically mutated at high frequency in primary endometrial cancer.
      ].
      The landscape of somatic mutations of ECs arising in the setting of CS has not been previously described. The EC and synchronous ovarian cancer (OC) as well as matched normal tissue of the case presented here have been subjected previously to whole-exome sequencing (reported in [
      • Schultheis A.M.
      • Ng C.K.
      • De Filippo M.R.
      • Piscuoglio S.
      • Macedo G.S.
      • Gatius S.
      • et al.
      Massively parallel sequencing-based clonality analysis of synchronous endometrioid endometrial and ovarian carcinomas.
      ]), which revealed that the EC and OC were clonally related and that the OC likely stemmed from a minor subclone of the EC (reported in [
      • Schultheis A.M.
      • Ng C.K.
      • De Filippo M.R.
      • Piscuoglio S.
      • Macedo G.S.
      • Gatius S.
      • et al.
      Massively parallel sequencing-based clonality analysis of synchronous endometrioid endometrial and ovarian carcinomas.
      ,
      • Moukarzel L.A.
      • Da Cruz Paula A.
      • Ferrando L.
      • Hoang T.
      • Sebastiao A.P.M.
      • Pareja F.
      • et al.
      Clonal relationship and directionality of progression of synchronous endometrial and ovarian carcinomas in patients with DNA mismatch repair-deficiency associated syndromes.
      ]). Reanalysis of the sequencing data together with the IHC profile revealed that the EC was of CN-L (endometrioid) molecular subtype (i.e. lacking POLE and TP53 mutations and MMR proficient). The EC and the OC harbored 36 and 34 non-synonymous somatic mutations, respectively, of which 20 were shared (Fig. 3A ). No somatic PTEN mutation was identified, however loss-of-heterozygosity of the wild-type allele was present in both the EC and OC (Fig. 3A). Akin to the mutations found in sporadic CN-L ECs, the Cowden-related EC and OC both harbored a CTNNB1 D32Y hotspot mutation as well as a PIK3R1 mutation. We have shown previously that almost 80% of sporadic CN-L ECs have a dominant mutational signature 1 related to aging [
      • Ashley C.W.
      • Da Cruz Paula A.
      • Kumar R.
      • Mandelker D.
      • Pei X.
      • Riaz N.
      • et al.
      Analysis of mutational signatures in primary and metastatic endometrial cancer reveals distinct patterns of DNA repair defects and shifts during tumor progression.
      ]. Similarly, this patient's EC displayed a dominant aging-related mutational signature 1 (Fig. 3B). As expected for an EC of CN-L molecular subtype, both the EC and OC were genomically relatively stable, and only few copy number alterations were found, including gains of chromosomes 1q, 7 and 10p, which were present in both the EC and the OC (Fig. 3C) [
      • Schultheis A.M.
      • Ng C.K.
      • De Filippo M.R.
      • Piscuoglio S.
      • Macedo G.S.
      • Gatius S.
      • et al.
      Massively parallel sequencing-based clonality analysis of synchronous endometrioid endometrial and ovarian carcinomas.
      ].
      Fig. 3
      Fig. 3Somatic genetic alterations of the Cowden syndrome-related endometrial and ovarian carcinoma.
      A, Repertoire of somatic mutations of the Cowden syndrome (CS) patient's primary endometrial (EC) and synchronous ovarian carcinoma (OC) subjected to whole-exome sequencing [
      • Schultheis A.M.
      • Ng C.K.
      • De Filippo M.R.
      • Piscuoglio S.
      • Macedo G.S.
      • Gatius S.
      • et al.
      Massively parallel sequencing-based clonality analysis of synchronous endometrioid endometrial and ovarian carcinomas.
      ,
      • Moukarzel L.A.
      • Da Cruz Paula A.
      • Ferrando L.
      • Hoang T.
      • Sebastiao A.P.M.
      • Pareja F.
      • et al.
      Clonal relationship and directionality of progression of synchronous endometrial and ovarian carcinomas in patients with DNA mismatch repair-deficiency associated syndromes.
      ]. Mutation types are color-coded according to the legend. Both the EC and the OC arising in this PTEN germline mutation carrier share somatic mutations, including a CTNNB1 hotspot mutation and a PIK3R1 mutation, suggesting that these two lesions are related rather than being two independent primary tumors. B, Mutational signatures provide information about the mutational processes, such as specific DNA repair deficiencies or DNA damage, that have occurred throughout tumor development [
      • Alexandrov L.B.
      • Nik-Zainal S.
      • Wedge D.C.
      • Aparicio S.A.
      • Behjati S.
      • Biankin A.V.
      • et al.
      Signatures of mutational processes in human cancer.
      ]. Mutational signatures of the EC (left) and the synchronous OC (right) defined by DeconstructSigs [
      • Rosenthal R.
      • McGranahan N.
      • Herrero J.
      • Taylor B.S.
      • Swanton C.
      DeconstructSigs: delineating mutational processes in single tumors distinguishes DNA repair deficiencies and patterns of carcinoma evolution.
      ] are shown. Akin to sporadic copy-number low (CN-L) ECs, which we have shown previously to harbor a dominant mutational signature 1 related to aging in the majority of cases [
      • Ashley C.W.
      • Da Cruz Paula A.
      • Kumar R.
      • Mandelker D.
      • Pei X.
      • Riaz N.
      • et al.
      Analysis of mutational signatures in primary and metastatic endometrial cancer reveals distinct patterns of DNA repair defects and shifts during tumor progression.
      ], both the EC and OC of this CS patient display a dominant aging-related mutational signature (signature 1) [
      • Schultheis A.M.
      • Ng C.K.
      • De Filippo M.R.
      • Piscuoglio S.
      • Macedo G.S.
      • Gatius S.
      • et al.
      Massively parallel sequencing-based clonality analysis of synchronous endometrioid endometrial and ovarian carcinomas.
      ,
      • Moukarzel L.A.
      • Da Cruz Paula A.
      • Ferrando L.
      • Hoang T.
      • Sebastiao A.P.M.
      • Pareja F.
      • et al.
      Clonal relationship and directionality of progression of synchronous endometrial and ovarian carcinomas in patients with DNA mismatch repair-deficiency associated syndromes.
      ], color-coded according to the legend. C, Copy number plots of the EC (top) and the OC (bottom) with the Log2-ratios plotted on the y-axis and the genomic positions on the x-axis [
      • Schultheis A.M.
      • Ng C.K.
      • De Filippo M.R.
      • Piscuoglio S.
      • Macedo G.S.
      • Gatius S.
      • et al.
      Massively parallel sequencing-based clonality analysis of synchronous endometrioid endometrial and ovarian carcinomas.
      ]. Both the EC and OC occurring in this CS patient share the same copy number gains and losses, including a 1q gain. D, Hierarchical cluster analysis of somatic mutations identified in 505 cancer-related genes [
      • Schultheis A.M.
      • de Bruijn I.
      • Selenica P.
      • Macedo G.S.
      • da Silva E.M.
      • Piscuoglio S.
      • et al.
      Genomic characterization of small cell carcinomas of the uterine cervix.
      ] using complete linkage and Euclidian distance metric, including the CS patient's EC from this study (Cowden_EC), which harbors a PTEN germline mutation and is of CN-L molecular subtype, and 77 sporadic PTEN-mutant ECs of CN-L molecular subtype from The Cancer Genome Atlas [
      • The Cancer Genome Atlas Research Network
      • Kandoth C.
      • Schultz N.
      • Cherniack A.D.
      • Akbani R.
      • Liu Y.
      • et al.
      Integrated genomic characterization of endometrial carcinoma.
      ]. This CS-related EC intermingles with the sporadic PTEN-mutant ECs, rather than forming a distinct cluster, suggesting that their somatic mutational profiles are similar.
      To compare whether the profile of somatic mutations affecting cancer-related genes in this CS-related EC harboring a germline PTEN mutation would be distinct from that of sporadic ECs with somatic PTEN mutations, we performed hierarchical cluster analysis, which groups tumors based on their similarity in mutation profiles. Using the CS-related EC described here and 77 sporadic PTEN-mutant ECs of CN-L molecular subtype from TCGA [
      • The Cancer Genome Atlas Research Network
      • Kandoth C.
      • Schultz N.
      • Cherniack A.D.
      • Akbani R.
      • Liu Y.
      • et al.
      Integrated genomic characterization of endometrial carcinoma.
      ] and a curated set of 505 cancer-related genes [
      • Schultheis A.M.
      • de Bruijn I.
      • Selenica P.
      • Macedo G.S.
      • da Silva E.M.
      • Piscuoglio S.
      • et al.
      Genomic characterization of small cell carcinomas of the uterine cervix.
      ], we found that the CS-related EC intermingled with the sporadic PTEN-mutant ECs rather than forming a separate branch/cluster (Fig. 3D). These findings provide evidence that the somatic cancer gene-related mutation profile of this CS patient's EC is consistent with that of sporadic CN-L PTEN-mutant ECs.

      7. Management of EC patients and therapies targeting the PTEN pathway

      Adjuvant therapy after primary EC surgery is determined by clinicopathologic features including age, histologic type, grade, stage and lymphovascular space invasion [
      • Colombo N.
      • Preti E.
      • Landoni F.
      • Carinelli S.
      • Colombo A.
      • Marini C.
      • et al.
      Endometrial cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up.
      ,
      • Koh W.J.
      • Abu-Rustum N.R.
      • Bean S.
      • Bradley K.
      • Campos S.M.
      • Cho K.R.
      • et al.
      Uterine neoplasms, version 1.2018, NCCN clinical practice guidelines in oncology.
      ]. For patients with stage III disease, as in this case, chemotherapy with radiation is often preferred to pelvic radiation alone based in part on the results of PORTEC-3 [
      • de Boer S.M.
      • Powell M.E.
      • Mileshkin L.
      • Katsaros D.
      • Bessette P.
      • Haie-Meder C.
      • et al.
      Adjuvant chemoradiotherapy versus radiotherapy alone for women with high-risk endometrial cancer (PORTEC-3): final results of an international, open-label, multicentre, randomised, phase 3 trial.
      ]. In recurrent disease, potentially curative treatment is largely based on location of recurrence and prior treatment [
      • Colombo N.
      • Preti E.
      • Landoni F.
      • Carinelli S.
      • Colombo A.
      • Marini C.
      • et al.
      Endometrial cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up.
      ,
      • Koh W.J.
      • Abu-Rustum N.R.
      • Bean S.
      • Bradley K.
      • Campos S.M.
      • Cho K.R.
      • et al.
      Uterine neoplasms, version 1.2018, NCCN clinical practice guidelines in oncology.
      ]. In the remaining women with widespread or distant recurrence, systemic therapies are recommended and include chemotherapy, immune-based therapies (with or without oral tyrosine kinase inhibitors, depending on microsatellite stable vs MSI-high status, respectively), hormonal therapies, and clinical trials. Although current treatment recommendations in primary and recurrent EC are based on clinicopathologic factors, emerging data have begun to associate prognosis and therapeutic responses with the four TCGA molecular subtypes. For example, a subgroup analysis of PORTEC-3 using TCGA molecular subtypes showed greater benefit for the addition of chemotherapy to pelvic RT in the CN-H and CN-L groups compared to the MSI and POLE groups [
      • Leon-Castillo A.
      • de Boer S.M.
      • Powell M.E.
      • Mileshkin L.R.
      • Mackay H.J.
      • Leary A.
      • et al.
      Molecular classification of the PORTEC-3 trial for high-risk endometrial cancer: impact on prognosis and benefit from adjuvant therapy.
      ], emphasizing the need for a targeted approach to treatment in this heterogeneous disease.
      Efforts to identify therapeutic targets for patients with PTEN-mutated EC have focused on the PI3K/AKT/mTOR pathway, as PTEN is a negative regulator of this cell growth and survival signaling pathway [
      • Salvesen H.B.
      • Haldorsen I.S.
      • Trovik J.
      Markers for individualised therapy in endometrial carcinoma.
      ,
      • Slomovitz B.M.
      • Coleman R.L.
      The PI3K/AKT/mTOR pathway as a therapeutic target in endometrial cancer.
      ,
      • Dedes K.J.
      • Wetterskog D.
      • Mendes-Pereira A.M.
      • Natrajan R.
      • Lambros M.B.
      • Geyer F.C.
      • et al.
      PTEN deficiency in endometrioid endometrial adenocarcinomas predicts sensitivity to PARP inhibitors.
      ]. It has been hypothesized that tumors with PTEN loss of function and subsequent activation of the mTOR pathway may preferentially respond to mTOR inhibitors [
      • Slomovitz B.M.
      • Coleman R.L.
      The PI3K/AKT/mTOR pathway as a therapeutic target in endometrial cancer.
      ,
      • Dedes K.J.
      • Wetterskog D.
      • Ashworth A.
      • Kaye S.B.
      • Reis-Filho J.S.
      Emerging therapeutic targets in endometrial cancer.
      ]; however, this has not borne out in clinical studies. The mTOR inhibitors everolimus [
      • Slomovitz B.M.
      • Lu K.H.
      • Johnston T.
      • Coleman R.L.
      • Munsell M.
      • Broaddus R.R.
      • et al.
      A phase 2 study of the oral mammalian target of rapamycin inhibitor, everolimus, in patients with recurrent endometrial carcinoma.
      ], temsirolimus [
      • Oza A.M.
      • Elit L.
      • Tsao M.S.
      • Kamel-Reid S.
      • Biagi J.
      • Provencher D.M.
      • et al.
      Phase II study of temsirolimus in women with recurrent or metastatic endometrial cancer: a trial of the NCIC clinical trials group.
      ], and ridaforolimus [
      • Oza A.M.
      • Pignata S.
      • Poveda A.
      • McCormack M.
      • Clamp A.
      • Schwartz B.
      • et al.
      Randomized phase II trial of ridaforolimus in advanced endometrial carcinoma.
      ] have modest single-agent activity in phase II studies, and everolimus with letrozole had an objective response rate (ORR) of 32% in recurrent EC, with particular efficacy in those with endometrioid histology [
      • Slomovitz B.M.
      • Jiang Y.
      • Yates M.S.
      • Soliman P.T.
      • Johnston T.
      • Nowakowski M.
      • et al.
      Phase II study of everolimus and letrozole in patients with recurrent endometrial carcinoma.
      ]. In a follow-up randomized phase II study of everolimus and letrozole versus standard of care hormonal therapy (GOG 3007), however, response rates were similar (ORR, 24% vs 22%, respectively) [
      • Slomovitz F.V.
      • Coleman R.L.
      • Walker J.L.
      • Fleury A.C.
      • Holman L.L.
      • Miller D.S.
      GOG 3007, a randomized phase II (RP2) trial of everolimus and letrozole (EL) or hormonal therapy (medroxyprogesterone acetate/tamoxifen, PT) in women with advanced, persistent or recurrent endometrial carcinoma (EC): a GOG Foundation study. Annual Meeting of the Society of Gynecologic Oncology. New Orleans 2018.
      ]. Additionally, a randomized phase II study of temsirolimus with or without megestrol acetate and tamoxifen (GOG 248) confirmed the modest activity of temsirolimus (ORR 22%), although the combination arm was stopped early due to an excess of venous thrombosis [
      • Fleming G.F.
      • Filiaci V.L.
      • Marzullo B.
      • Zaino R.J.
      • Davidson S.A.
      • Pearl M.
      • et al.
      Temsirolimus with or without megestrol acetate and tamoxifen for endometrial cancer: a gynecologic oncology group study.
      ]. Tumor mutational analysis of GOG248 found no association between PTEN mutation and efficacy of temsirolimus [
      • Myers A.P.
      • Filiaci V.L.
      • Zhang Y.
      • Pearl M.
      • Behbakht K.
      • Makker V.
      • et al.
      Tumor mutational analysis of GOG248, a phase II study of temsirolimus or temsirolimus and alternating megestrol acetate and tamoxifen for advanced endometrial cancer (EC): an NRG oncology/gynecologic oncology group study.
      ]. In CS patients specifically, studies have investigated the impact of mTOR inhibitors on dermatologic, endoscopic, and neurologic symptoms. One study of 18 CS patients reported that 67% of patients experienced improved symptoms after a 56-day course of sirolimus [
      • Komiya T.
      • Blumenthal G.M.
      • DeChowdhury R.
      • Fioravanti S.
      • Ballas M.S.
      • Morris J.
      • et al.
      A pilot study of sirolimus in subjects with cowden syndrome or other syndromes characterized by germline mutations in PTEN.
      ], and it was proposed that sirolimus may be investigated as a prophylactic agent in prevention of malignancy in these patients.
      More recent studies have investigated therapies targeting other components of the PI3K/AKT/mTOR pathway, including PI3K, AKT, and dual inhibitors, with minimal activity noted [
      • Roncolato F.
      • Lindemann K.
      • Willson M.L.
      • Martyn J.
      • Mileshkin L.
      PI3K/AKT/mTOR inhibitors for advanced or recurrent endometrial cancer.
      ]. Many PI3K inhibitor clinical trials were limited by significant toxicity [
      • Makker V.
      • Recio F.O.
      • Ma L.
      • Matulonis U.A.
      • Lauchle J.O.
      • Parmar H.
      • et al.
      A multicenter, single-arm, open-label, phase 2 study of apitolisib (GDC-0980) for the treatment of recurrent or persistent endometrial carcinoma (MAGGIE study).
      ,
      • Heudel P.E.
      • Fabbro M.
      • Roemer-Becuwe C.
      • Kaminsky M.C.
      • Arnaud A.
      • Joly F.
      • et al.
      Phase II study of the PI3K inhibitor BKM120 in patients with advanced or recurrent endometrial carcinoma: a stratified type I-type II study from the GINECO group.
      ]. A recent study of the dual PI3K/mTOR inhibitor samotolisib (LY3023414) reported an ORR of 16% with manageable safety profile in a population selected for PI3K pathway mutations, including PTEN [
      • Rubinstein M.M.
      • Hyman D.M.
      • Caird I.
      • Won H.
      • Soldan K.
      • Seier K.
      • et al.
      Phase 2 study of LY3023414 in patients with advanced endometrial cancer harboring activating mutations in the PI3K pathway.
      ]. Similarly, studies of AKT inhibitors have also been limited by toxicity and report minimal activity [
      • Westin S.N.
      • Sill M.W.
      • Coleman R.L.
      • Waggoner S.
      • Moore K.N.
      • Mathews C.A.
      • et al.
      Safety lead-in of the MEK inhibitor trametinib in combination with GSK2141795, an AKT inhibitor, in patients with recurrent endometrial cancer: an NRG oncology/GOG study.
      ,
      • Myers A.P.
      • Konstantinopoulos P.A.
      • Barry W.T.
      • Luo W.
      • Broaddus R.R.
      • Makker V.
      • et al.
      Phase II, 2-stage, 2-arm, PIK3CA mutation stratified trial of MK-2206 in recurrent endometrial cancer.
      ]. A phase I study of the oral AKT inhibitor GSK2141795 did report two partial responses, one in a patient with PTEN loss observed in her tumor [
      • Aghajanian C.
      • Bell-McGuinn K.M.
      • Burris 3rd, H.A.
      • Siu L.L.
      • Stayner L.A.
      • Wheler J.J.
      • et al.
      A phase I, open-label, two-stage study to investigate the safety, tolerability, pharmacokinetics, and pharmacodynamics of the oral AKT inhibitor GSK2141795 in patients with solid tumors.
      ].
      ECs are associated with obesity, and there is an increasing appreciation for the role of the PI3K pathway in driving insulin resistance and cancer growth. This has spurred the investigation of metabolic therapies for EC [
      • Kyo S.
      • Nakayama K.
      Endometrial cancer as a metabolic disease with dysregulated PI3K signaling: shedding light on novel therapeutic strategies.
      ,
      • Hopkins B.D.
      • Pauli C.
      • Du X.
      • Wang D.G.
      • Li X.
      • Wu D.
      • et al.
      Suppression of insulin feedback enhances the efficacy of PI3K inhibitors.
      ]. Preclinical studies have shown promising activity for metformin in EC cell lines [
      • Pabona J.M.P.
      • Burnett A.F.
      • Brown D.M.
      • Quick C.M.
      • Simmen F.A.
      • Montales M.T.E.
      • et al.
      Metformin promotes anti-tumor biomarkers in human endometrial cancer cells.
      ,
      • Qiang P.
      • Shao Y.
      • Sun Y.P.
      • Zhang J.
      • Chen L.J.
      Metformin inhibits proliferation and migration of endometrial cancer cells through regulating PI3K/AKT/MDM2 pathway.
      ]. The addition of metformin to everolimus and letrozole, however, resulted in similar results to previous trials of everolimus and letrozole and standard of care hormonal therapy [
      • Soliman P.T.
      • Westin S.N.
      • Iglesias D.A.
      • Fellman B.M.
      • Yuan Y.
      • Zhang Q.
      • et al.
      Everolimus, letrozole, and metformin in women with advanced or recurrent endometrioid endometrial cancer: a multi-center, single arm, Phase II Study.
      ]. Furthermore, GOG 286 (NCT02065687), a randomized phase II/III study of paclitaxel/carboplatin with and without metformin in Stage III or IVA, Stage IVB, or recurrent EC showed no additional benefit to the addition of metformin [
      • Bae-Jump S.M.
      • Gehrig P.A.
      • Moxley K.
      • Hagemann A.R.
      • Waggoner S.E.
      • O’Cearbhaill R.E.
      • Mc Donald M.
      • Di Silvestro P.A.
      • Sperduto P.
      • Aghajanian C.
      A randomized phase II/III study of paclitaxel/carboplatin/metformin versus paclitaxel/carboplatin/placebo as initial therapy for measurable stage III or IVA, stage IV, or recurrent endometrial cancer: an NRG oncology/GOG study.
      ]. Novel studies are also looking at the role of a ketogenic diet in newly diagnosed, obese and overweight EC patients (NCT03285152), an intervention which has been shown to be safe in regards to blood lipid levels [
      • Cohen C.W.
      • Fontaine K.R.
      • Arend R.C.
      • Gower B.A.
      A Ketogenic diet is acceptable in women with ovarian and endometrial cancer and has no adverse effects on blood lipids: a randomized.
      ].
      Ultimately, the PI3K/PTEN pathway is critical in many ECs, including in patients with CS. An understanding of this pathway and its targeted therapies is necessary for the ongoing improvement in the treatment of EC, both in CS patients and in the 55–65% of sporadic EC patients whose tumors harbor a somatic PTEN mutation.

      8. Case resolution

      Several months after CS diagnosis, the patient developed a headache accompanied by visual disturbances. A brain MRI demonstrated a right cerebellar lesion with significant mass effect and fourth ventricular effacement resulting in supratentorial obstructive hydrocephalus and incipient signs of transtentorial herniation (Fig. 4A ). The patient underwent surgical resection of the tumor by suboccipital craniectomy. Pathologic examination demonstrated a dysplastic gangliocytoma of the cerebellum (Lhermitte-Duclos), grade I (WHO; Fig. 4B).
      Fig. 4
      Fig. 4Pre-operative imaging of the posterior cranial fossa.
      A, Axial T2 weighted magnetic resonance (MR) image shows a hyperintense lesion with folial thickening in the right cerebellum, a characteristic finding of dysplastic cerebellar ganglioytoma (Lhermitte-Duclos disease). B, Representative hematoxylin and eosin-stained section (20×) showing the histologic features of the dysplastic gangliocytoma of the cerebellum with dysplastic ganglion cells. Scale bar, 50 μm.
      Following her craniectomy, the patient began multidisciplinary follow-up per NCCN screening guidelines. Thyroid ultrasound and colonoscopy revealed a multinodular goiter and colonic hamartomatous polyp. A risk-reducing bilateral mastectomy was performed with preservation of the areola-nipple complex. The patient also underwent a total thyroidectomy, and pathologic analysis confirmed the diagnosis of goiter.
      Thirty months after her initial EC surgery, a PET-CT demonstrated a pulmonary mass. The patient was subjected to a segmentectomy of the right superior lobe with mediastinal lymph node dissection. Pathologic examination demonstrated 1.3 cm metastatic ER-positive endometrioid adenocarcinoma of similar histologic grade as the primary EC. Eight mediastinal lymph nodes were negative for neoplasia. As the platinum-free interval was five and a half years, the patient subsequently underwent six cycles of carboplatin and paclitaxel. The case was discussed in the institutional multidisciplinary tumor board. Several possibilities were considered, including inhibition of the PI3K pathway, but maintenance therapy with letrozole was chosen given the tumor's ER positivity. This led to prolonged remission, and the patient remains alive without evidence of disease ten years following her initial presentation.

      Author contributions

      N. Tuset, M. Gil, S. Gatius and X. Matias-Guiu contributed to the treatment of the patient. The manuscript was drafted by B.L. Manning-Geist, Y. Liu and B. Weigelt. Pathology expertise was provided by S. Gatius and X. Matias-Guiu, radiology expertise by M. Gil, gynecologic medical oncology expertise by Y. Liu, N. Tuset, B.L. Manning-Geist, N.R. Abu-Rustum and C. Aghajanian, clinical genetics expertise by Y. Liu, and molecular genomics expertise by A. Da Cruz Paula and B. Weigelt. All authors were involved in the process of discussing, reviewing and editing the manuscript.

      Declaration of Competing Interest

      Y. Liu reports grants from AstraZeneca and GSK/Tesaro, outside the submitted work. NRA-R reports grants from Stryker/Novadaq and GRAIL paid to the institution, outside the submitted work. C. Aghajanian reports grants from Clovis, Genentech, AbbVie and AstraZeneca, and membership of advisory boards of Tesaro, Eisai/Merck, Mersana Therapeutics, Roche/Genentech, Abbvie, AstraZeneca/Merck and Repare Therapeutics, all outside the submitted work. B. Weigelt reports ad hoc membership of the advisory board of Repare Therapeutics, outside the scope of this study. The remaining authors have no conflicts of interest to declare.

      Acknowledgements

      We thank Amanda Catchings, MGC, CGC (Memorial Sloan Kettering Cancer Center, New York, USA) for assistance with the literature review and Lorenzo Ferrando (University of Genoa, Genoa, Italy) for assistance with the hierarchical cluster analysis.
      B. Weigelt is funded in part by Breast Cancer Research Foundation, Cycle for Survival and Stand Up To Cancer grants. Research reported in this publication was supported in part by a Cancer Center Support Grant of the NIH/NCI (Grant No. P30CA008748 ), and by Grupos Estables Asociación Española contra el Cáncer, Spain.

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