Estrogen replacement therapy withdrawal and regression of metastatic breast cancer

Background. Data regarding the effects of estrogen replacement therapy (ERT) and its withdrawal in patients with breast cancer are limited. Methods. Four cases were observed involving estrogen replacement therapy withdrawal as management of metastatic breast cancer. Results. Three patients with a history of primary breast cancer developed metastatic disease while on ERT. A fourth patient presented with metastatic breast cancer while on ERT. Withdrawal of this «physiologic» ERT alone as the only therapeutic intervention resulted in regression of metastatic disease in all four patients. Conclusions. In patients receiving ERT who develop metastatic breast cancer, withdrawal of ERT alone is a therapeutic option. Awareness of this phenomenon may be of value in management of these patients. The role of ERT and value of ERT withdrawal in patients with breast cancer deserve further study