Combination of beta-interferon and tamoxifen as a new way to overcome clinical resistance to tamoxifen in advanced breast cancer.

This paper shows that the response to tamoxifen (T) can be improved and the resistance to the antiestrogen can be overcome, in advanced breast cancer, by a pretreatment with natural beta-interferon (nIFN-beta) followed by the association of nIFN-beta with T. Forty-three patients with advanced breast cancer, both progressive (group A) and stable or partially responsive (group B) to previous treatment with T received nIFN-beta i.m. 3 x 10(6) IU/day for 14 days and, subsequently, T30 mg/day and nIFN-beta once a week. The overall objective response rate was 26% (95% Confidence Interval = 13-39) with 8 PR obtained in group A and 3 CR in group B. The median duration of response was 6 months (range 3-12+). Stabilization of disease was observed in 44% of cases. Toxicity was mild.