Efficacy of chemotherapy after hormone therapy for hormone receptor–positive metastatic breast cancer

OBJECTIVE: According to the guidelines for metastatic breast cancer, hormone therapy for hormone receptor–positive metastatic breast cancer without life-threatening metastasis should be received prior to chemotherapy. Previous trials have investigated the sensitivity of chemotherapy for preoperative breast cancer based on the efficacy of neoadjuvant hormone therapy. In this retrospective study, we investigated the efficacy of chemotherapy for metastatic breast cancer in hormone therapy–effective and hormone therapy–ineffective cases. METHODS: Patients who received chemotherapy after hormone therapy for metastatic breast cancer between 2006 and 2013 at our institution were investigated. RESULTS: A total of 32 patients received chemotherapy after hormone therapy for metastatic breast cancer. The median patient age was 59 years, and most of the primary tumors exhibited a T2 status. A total of 26 patients had an N(+) status, while 7 patients had human epidermal growth factor receptor 2–positive tumors. A total of 13 patients received clinical benefits from hormone therapy, with a rate of clinical benefit of subsequent chemotherapy of 30.8%, which was not significantly different from that observed in the hormone therapy–ineffective patients (52.6%). A total of 13 patients were able to continue the hormone therapy for more than 1 year, with a rate of clinical benefit of chemotherapy of 38.5%, which was not significantly different from that observed in the short-term hormone therapy patients (47.4%). The luminal A patients were able to continue hormone therapy for a significantly longer period than the non-luminal A patients (median survival time: 17.8 months vs 6.35 months, p = 0.0085). However, there were no significant differences in the response to or duration of chemotherapy. CONCLUSION: The efficacy of chemotherapy for metastatic breast cancer cannot be predicted based on the efficacy of prior hormone therapy or tumor subtype, and clinicians should administer chemotherapy in all cases of hormone receptor–positive metastatic breast cancer, if needed.