Endocrine and clinical effects of an LHRH analogue in pretreated advanced breast cancer.

Buserelin represents one of the main LHRH analogues. It appears to be effective in untreated metastatic breast cancer, whereas its activity in pretreated advanced patients remains to be established. To evaluate endocrine and clinical effects of buserelin in pretreated advanced mammary carcinoma, 14 postmenopausal women with metastatic breast cancer, which had been previously treated with hormones and/or chemotherapy, entered the study. Buserelin was subcutaneously injected at a daily dose of 1.5 mg for 7 days, then intranasally at a daily dose of 1.2 mg until progression. Before and after the 7 days of subcutaneous administration of the LHRH analogue, FSH, LH, estradiol, testosterone basal serum levels, and PRL response to TRH were examined. After the 7 days of buserelin subcutaneous injection, a significant decrease in FSH, LH and estradiol values was observed, whereas testosterone was not affected. PRL response to TRH did not change after buserelin subcutaneous treatment in 8 patients, it decreased in one and was completely abolished in the last 5 cases. All patients whose PRL response to TRH did not decrease had a progression within the first month of therapy, whereas only 1 of 6 patients whose PRL response to TRH was reduced or abolished following buserelin administration showed a progression. Among the other 5 cases, 2 minor responses and 3 stable diseases were achieved. These preliminary results suggest that buserelin has only a limited effectiveness in metastatic breast cancer patients who have been previously treated with hormones and/or chemotherapy, and that its activity in the control of tumor growth is associated with a reduction in PRL secretion.