HBOC syndrome with an uncharacterized variant in the BRCA1 gene in a patient diagnosed with endometrial cancer after surgery for bilateral breast cancer: A case report

The association between endometrial cancer and the BRCA1 and BRCA2 genes is not fully understood, and the risk elevation of endometrial cancer in patients with hereditary breast and ovarian cancer (HBOC) is not understood. The present report examines a rare case of HBOC syndrome and an uncharacterized variant of the BRCA1 gene in a patient diagnosed with endometrial cancer. A 46-year-old woman, gravida 1 para 1, was referred to Wakayama Medical University Hospital (Wakayama, Japan) because positron emission tomography/computed tomography (PET/CT) showed a high FDG uptake in the corpus uteri and the left ovary. PET/CT was performed just after mastectomy for left-sided breast cancer (triple negative). The patient had previously undergone partial mastectomy for right-sided breast cancer (triple negative) and was treated with radiation therapy to the right residual breast when she was 39 years old. Laparoscopic hysterectomy and bilateral adnexectomy were performed, and the histological diagnosis was endometrioid carcinoma, grade 1. Her germline BRCA status was tested by blood examination and the result was ‘NM_007294.4(BRCA1):c.49G>C (p.Ala17Pro)’. The variant was evaluated as ‘likely pathogenic’. The patient was diagnosed with HBOC syndrome and endometrial cancer, pT1ANxM0. The patient had no recurrence of breast or endometrial cancer 16 months after gynecologic surgery.