A Case of Triple-Negative Breast Cancer with Germline Pathogenic Variants in Both BRCA1 and BRCA2

Abstract We report a rare case of hereditary breast and ovarian cancer syndrome (HBOC) with pathogenic variants in both BRCA1 and BRCA2. The patient was a 78-year-old woman who visited the hospital after noticing a lump in her left breast 6 months before, which gradually increased in size. According to her family history, her maternal aunt developed breast cancer in her 40s. On palpation, a 4-cm large mass was palpated in the upper outer part of the left breast. A needle biopsy revealed invasive ductal carcinoma of the breast, which was negative for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor type 2. The patient was diagnosed with cT2N0M0 stage IIA, and primary systemic treatment was planned. The patient developed drug-induced interstitial pneumonia after receiving paclitaxel. Although she recovered spontaneously, she did not wish to receive further chemotherapy, and thus surgery was performed. Four months after the surgery, the patient became aware of dyspnea. After a thorough examination, she was diagnosed with postoperative cancer recurrence of the left breast with multiple liver metastases, cancerous peritonitis, multiple bone metastases, and multiple lymph node metastases. Genetic testing was performed, and pathogenic variants were found in both BRAC1 and BRCA2. However, her condition worsened, and she died 8 months after the surgery. BRCA pathogenic variants had more advanced breast cancer on initial diagnosis and worse cancer-related outcomes. It is desirable to consider the optimal approach to the treatment of breast cancer in pathogenic variants. In elderly patients with triple-negative breast cancer, HBOC may be suspected, based on biomarkers and family history. It is important to provide information on genetic counseling, genetic testing, and effective treatment plans proactively.