OBJECTIVES: Recent data have suggested that the efficacy of cancer chemotherapy does not depend only on tumor-related characteristics, but also on patient biological status, namely immune and endocrine functions. In particular, it has been shown that prolactin (PRL) is a growth factor for breast cancer, and abnormally high blood levels of PRL have been described in metastatic breast cancer patients. The present study was performed to evaluate the efficacy of chemotherapy with taxanes in relation to PRL blood levels in metastatic breast cancer.
MATERIAL & METHODS: The study included 20 metastatic breast cancer patients, who were treated with taxotere (100 mg/mq I.V. every 21 days) for at least 3 consecutive cycles. Serum levels of PRL were measured by RIA before the onset of treatment and at 21-days intervals.
RESULTS: The clinical response consisted of partial response (PR) in 6, stable disease (SD) in 7 and progressive disease (PD) in the remaining 7 patients. Abnormally high pre-treatment levels of PRL were seen in 7/20 patients. The percent of patients who had PD in response to chemotherapy was significantly high in patients with pre-treatment hyperprolactinemia than in those with normal blood levels of PRL before therapy.
CONCLUSIONS: This study shows that the evidence of abnormally high serum levels of PRL correlates with resistance to chemotherapy with taxanes in metastatic breast cancer. Therefore, a concomitant administration of anti-prolactinemic agents, such as bromocriptine, could enhance the efficacy of chemotherapy itself.