Results of endocrine therapy do not predict response to chemotherapy in advanced breast cancer.

One hundred and four patients with advanced breast cancer treated with adriamycin +/- vincristine had had prior endocrine therapy. Of 28 responders to prior endocrine therapy a response to subsequent chemotherapy occurred in 15 (54%); the response frequency in the 76 non-responders to endocrine therapy was 51% (39 patients). The median time to treatment failure was not significantly different between responders to prior endocrine treatment and non-responders (7 months vs 5 months; P = 0.136). Although the median survival from starting chemotherapy tended to be longer in the endocrine responders (18 months) than in the non-responders (12 months), there was no significant difference between the two groups (chi = 2.749; P = 0.097). In a subgroup of 31 non-responders to endocrine therapy who had had stable disease (greater than or equal to 6 months) the median time to treatment failure was 6 months and median survival 13 months. This lack of differences existed for each subgroup of endocrine therapy. Response to prior endocrine treatment was not shown to be a determinant of response to subsequent chemotherapy.