HER2-positive apocrine breast cancer: chemotherapy and Herceptin

What happened, in summary

A 65-year-old woman had 3 months of persistent pain in her right breast. Examination found a mobile 3 cm lump in the upper outer quadrant. Mammography showed a 27 x 17 mm suspicious nodule, and biopsy confirmed apocrine breast cancer, a rare breast cancer subtype. The tumor was ER-negative and PR-negative, with HER2 expression in 65% of cells and androgen receptor expression in 63% of cells. CT imaging showed the breast mass and abnormal axillary lymph nodes but no distant metastases. She had tumor excision of the right breast with surgical axillary staging. Final pathology showed a 1.8 cm Grade II apocrine breast cancer with no in situ component or vascular emboli. Seven of 17 dissected lymph nodes contained metastasis. The TNM classification was pT1c pN2a M0, so the cancer was node-positive but non-metastatic; Grade II and TNM staging were reported rather than a simple Stage II diagnosis. After surgery, she received adjuvant chemotherapy: 3 rounds of anthracycline plus cyclophosphamide, followed by 3 cycles of paclitaxel. Herceptin was given during the paclitaxel cycles and then continued alone, for 17 Herceptin doses total. Four weeks after paclitaxel, she completed radiotherapy to the right breast and supraclavicular area: 42 Gy in 15 fractions plus an 11.2 Gy tumor-bed boost in 4 fractions. No significant treatment complications were reported. Surveillance included clinical exams, mammography every 3 months, and annual CT. At 2-year follow-up, she remained disease-free with no lymph-node recurrence or distant metastases.