Metastatic Breast Cancer With Durable Liver and Peritoneal Response to Eribulin

What happened, in summary

A 55-year-old woman underwent left quadrantectomy and axillary lymph-node dissection in 1998 for invasive ductal breast carcinoma. The original tumor was ER 90% and PgR 70%. She completed 6 cycles of CMF chemotherapy, received radiation and then took tamoxifen for 5 years. In 2010, follow-up imaging found a liver lesion and several peritoneal lesions. Biopsy of the liver confirmed metastatic breast cancer with ER 60%, PgR 20%, HER2 1+ and Ki67 10%. Six cycles of FEC chemotherapy produced a complete response in the liver and omental disease. She then received anastrozole until peritoneal progression in 2013. Docetaxel produced a partial response over 8 cycles, after which she switched to fulvestrant. By 2015, 2 liver lesions measuring 4.5 cm and 3.8 cm were present along with worsening omental disease, fatigue, appetite loss and weight loss. She began eribulin in May 2015. The treatment continued for at least 34 cycles. Her performance status improved, and side effects remained relatively limited. After 6 cycles, the liver disease had shrunk by more than 50% and the peritoneal disease had completely responded. Later imaging continued to show stable liver disease and a persistent peritoneal response while eribulin remained ongoing.