Efficacy of tamoxifen following anastrozole ('Arimidex') compared with anastrozole following tamoxifen as first-line treatment for advanced breast cancer in postmenopausal women

Abstract

Anastrozole ('Arimidex') is indicated for the treatment of advanced breast cancer in postmenopausal women. Combined analysis of two international randomised, double-blind trials (n=1021) showed that in patients with hormone receptor-positive tumours, first-line treatment with anastrozole significantly prolonged the time to progression (TTP) compared with tamoxifen (median TTP: 10.7 versus 6.4 months, respectively; P=0.022). Second-line tamoxifen following anastrozole, or vice versa, in this trial population was unblinded. The treatments were crossed over and then efficacy was assessed using a questionnaire. Of 511 patients randomised to anastrozole, 137 (26.8%) received second-line tamoxifen. Questionnaire data were available for 119 patients; 58 (48.7%) gained clinical benefit (CB=complete+partial response (CR+PR)+(stable disease (SD) >/=24 weeks)), while 12 (10.1%) had an objective response (OR=CR+PR). Of 510 patients randomised to tamoxifen, 134 (26.3%) received second-line anastrozole. Questionnaire data from 95 patients showed that 54 (56.8%) gained CB and 7 of the patients gaining CB (7.4%) had an OR. Previous studies showed anastrozole is effective after first-line tamoxifen. These data show that the sequential administration of first-line anastrozole followed by tamoxifen provides effective use of these drugs in the treatment of postmenopausal women with advanced breast cancer.