Adjuvant hormone therapy for breast cancer: alternatives to tamoxifen.Prescrire Int. 2005 Jun; 14(77):108-10.PI
(1) After surgical excision of hormone-receptor-positive non metastatic breast cancer in postmenopausal women, a meta-analysis of 55 trials has shown that adjuvant tamoxifen, 20 mg/day for 5 years, reduces the risk of relapse by 8% and the risk of death by 5% (absolute values). The benefit of treatment beyond 5 years remains to be established. (2) Preliminary four-year results from a double-blind randomised controlled trial comparing anastrozole with tamoxifen (ATAC trial) indicated an advantage for anastrozole in reducing the risk of relapse. There was no difference in survival rate. Women taking anastrozole experienced more sexual dysfunction and an increased risk of osteoporotic fractures, whereas tamoxifen was associated with an increased risk of thrombosis and endometrial cancer. The trial's methodology is controversial, however, and conclusions concerning the relative risk-benefit balances of these two drugs must await the full 5-year results. (3) A double-blind placebo-controlled trial of letrozole, prescribed after 5 years of adjuvant tamoxifen, was stopped early after a median follow-up of 2.4 years. When extrapolated to 4 years, the results suggest that letrozole reduced the risk of relapse (7%, compared to 13% with tamoxifen) but had no effect on survival. (4) A double-blind trial comparing tamoxifen with exemestane in 4742 women who had already received tamoxifen for two to three years showed a higher three-year disease-free survival rate with exemestane (91.5% versus 86.8%). Overall survival did not differ between the two groups. (5) Pending results of further clinical trials, tamoxifen remains the first-line adjuvant hormone therapy for most postmenopausal women with hormone-receptor-positive non metastatic breast cancer.