Stage 3 breast cancer: complete pathological response to chemotherapy

What happened, in summary

This 61-year-old postmenopausal woman had neurofibromatosis type 1 since childhood, with multiple neurofibromas, café-au-lait macules, freckling, pectus carinatum, and a markedly enlarged right breast. During a surgical consultation about the enlarged right breast, a surgeon noticed a separate mass in the left breast. Mammogram and ultrasound showed a 7.6 × 6.4 cm irregular mass in the upper outer quadrant of the left breast and an enlarged axillary lymph node measuring 2 × 4 cm. Tru-cut biopsy confirmed invasive lobular carcinoma. CT also showed the left breast mass with overlying skin thickening, and the cancer was staged cT3N1M0 / Stage III. Biomarker testing showed ER-positive and PR-positive disease, with HER2/neu negative. She received 4 cycles of neoadjuvant doxorubicin plus cyclophosphamide. She then underwent left modified radical mastectomy with left axillary lymph-node dissection. Pathology showed no residual tumor, free skin, nipple, and surgical margins, and 6 reactive lymph nodes, consistent with complete pathologic response in the breast and axilla. After surgery, she received 4 cycles of adjuvant paclitaxel. Endocrine therapy began with anastrozole, but severe muscle pain and osteoporosis led to a change to tamoxifen 20 mg daily. One year later, CT detected a thyroid nodule, but fine-needle aspiration showed no malignancy and no other suspicious findings were present. At 1-year follow-up, she remained free of disease and was referred for plastic surgery evaluation for the enlarged right breast related to neurofibromatosis. Her course is notable because the cancer was found incidentally during care for neurofibromatosis-related breast enlargement rather than through a planned screening visit.