Prolonged complete response after treatment withdrawal in HER2-overexpressed, hormone receptor-negative breast cancer with liver metastases: the prospect of disappearance of an incurable disease

BACKGROUND: Metastatic breast cancer has consistently been viewed as a non-curable disease. Specific palliative treatments such as chemotherapy and hormone therapy have resulted in a mean overall survival of approximately 30 months. While cases of prolonged complete response have been reported with hormone or trastuzumab monotherapy, rendering metastatic breast cancer a chronic disease, any treatment withdrawal has ineluctably led to relapse. Prolonged remission without any anti-cancer treatment has never been reported to our knowledge. CASE PRESENTATION: We report here the unique observation of the spontaneous evolution of two breast cancer patients with synchronous liver metastases who decided to stop trastuzumab after achieving complete response. They were Caucasian women with synchronous liver metastatic breast carcinoma. Both breast cancers reached skin and regional lymph nodes. There were several liver metastases in both patients. They received surgery, radiotherapy and chemotherapy combined with trastuzumab. They decided to stop their treatment, despite guidelines. After a follow-up longer than 20 months, they did not relapse clinically, radiologically, and biologically. CONCLUSION: This findings question the belief of the unavoidability of recurrence of metastatic breast cancer, specifically in the liver. It opens up the unprecedented possibility of a cure-like state in exceptional and probably special cases.