Megestrol acetate plus alpha 2a interferon as second line therapy for postmenopausal patients with advanced breast cancer: results of a multicentric phase II trial.

This phase II study was aimed to evaluate the activity of a combination of megestrol acetate (MA) and alpha 2a interferon (IFN) in a group of tamoxifen-responsive breast cancer patients. Thirty patients with metastatic breast cancer either previously treated with adjuvant tamoxifen for at least 24 months or treated with tamoxifen for metastatic disease and showing an objective response or stability of disease, were given MA (single daily dose of 160 mg per os) and alpha 2a IFN (3 million units-MU-three times per week intramuscularly-i.m.-). Of the 29 evaluable patients, 2 (6.8%) achieved a complete response and 4 (13.8%) a partial response for an overall response rate of 20.6% (95% confidence limits = 5.9%-35.4%). Treatment toxicity was mild and no patient had to discontinue or delay the treatment due to IFN side effects. Our results seem to rule out that alpha 2a IFN is able to improve the activity of MA as second-line therapy in tamoxifen-responsive patients.