Recurrent HER2-amplified breast cancer: complete remission on trastuzumab-based therapy

What happened, in summary

This 49-year-old premenopausal woman had a total mastectomy and sentinel lymph-node biopsy in April 2003 for Stage I invasive ductal carcinoma of the right breast. The sentinel node had no metastasis. The original tumor was ER-negative, PR-negative, HER2 IHC 1+, and HER2 non-amplified by FISH, with a ratio of 1.1. She received adjuvant chemotherapy with 4 cycles of epirubicin and cyclophosphamide every 3 weeks. After chemotherapy, she became postmenopausal and was followed without further treatment. Six years and 10 months after the first surgery, she noticed lumps in her left axilla. Ultrasound and CT showed swelling in left axillary and infraclavicular lymph nodes, and FDG-PET showed uptake in those areas. Fine-needle aspiration of a left axillary node confirmed breast cancer metastasis. The recurrent disease had a different biomarker profile from the original tumor: it was ER-positive, PR-positive, and HER2-amplified by FISH with a ratio of 5.7. PET-CT did not show other metastases or a malignancy in another organ, including the left breast, so the team considered either recurrence from the right breast cancer or an occult left breast cancer. Weekly paclitaxel with weekly trastuzumab was started before any local surgery, partly to test treatment responsiveness. After 3 courses, PET-CT showed complete remission of the swollen lymph nodes and no FDG uptake, and the elevated CEA normalized. She continued paclitaxel plus trastuzumab for 1 year and remained in complete remission with tolerable neuropathy. She then continued trastuzumab alone, while additional local treatment with radiotherapy or surgery was being considered.