A phase III comparison of two toremifene doses to tamoxifen in postmenopausal women with advanced breast cancer

Efficacy and safety of toremifene 60 and 240 mg daily (TOR60 and TOR240) are compared to 40 mg tamoxifen daily (TAM40) in postmenopausal women with advanced estrogen receptor (ER) positive or ER unknown breast cancer. The study is randomized and open label in three parallel groups. Primary efficacy variables are response rate and time to progression. WHO and ECOG criteria were used for measurable and nonmeasurable disease assessment, respectively. Safety was reported according to WHO criteria. Altogether 463 patients were randomized (157 to TOR60, 157 to TOR240, and 149 to TAM40). By data cut-off, after 20.5 months median follow-up time, over 70% of the patients had experienced disease progression. Response rates are 20.4%, 28.7%, and 20.8% in TOR60, TOR240, and TAM40, respectively. TOR60 and TAM40 show statistically equivalent efficacy and the difference between TOR240 and TAM40 is not significant (P = 0.112). Median times to progression are 4.9 (TOR60), 6.1 (TOR240), and 5.0 (TAM40) months and the corresponding hazard ratios (TAM:TOR) 1.015 and 1.124. Again, TOR60 and TAM40 are statistically equivalent and the difference between TOR240 and TAM40 is not significant (P = 0.374). All treatments were well tolerated. As a conclusion, TOR60 and TAM40 show equivalent clinical efficacy and tolerability. The higher dose of toremifene slightly but not statistically significantly improves response rate and time to progression. In postmenopausal women, toremifene 60 mg daily is an effective and safe treatment of advanced ER-positive or ER-unknown breast cancer.