Tamoxifen (T) compared to placebo (P), after adjuvant chemotherapy (CT), in premenopausal women with early breast cancer (EBC): Interim results of NCIC-CTG MA.12

Abstract

547 Background: In the early 1990’s, the role of adjuvant T in premenopausal women with EBC had not been clearly established. The efficacy of adjuvant T in hormone receptor (H) negative EBC was unclear. Methods: Eligible premenopausal women with node (N) +ve/high risk N -ve EBC, any H status, post surgery, received standard adjuvant CT (AC ×4, CMF ×6, CEF x6) then were randomized to T (20 mg/day) or P for 5 yrs. Overall survival (OS), disease-free survival (DFS) and toxicity/compliance were evaluated. Original sample size was 800 pts but based on slow accrual was reduced to 660. Mortality rate is lower than anticipated, and Data Safety Monitoring Committee approved reporting results after second interim analysis (152 deaths). Results: 1993–2000, 672 women randomized, median follow-up 8.4 yrs. For T vs P, 5 yr OS 87% vs 82% [Hazard Ratio HR 0.81 (95% CI 0.58–1.12), p = 0.19] and 5 yr DFS 78% vs 71% [HR 0.79 (95% CI 0.61–1.03), p = 0.09]. HR for OS (0.87 vs 0.78, p = 0.71) and DFS (0.79 vs 0.77, p = 0.87) were not significantly different for H +ve and H -ve tumors respectively. Compliance with T/P was suboptimal, 29% women stopping treatment within 2 yrs, and only 53% completing 5 yrs. Conclusions: Current results show only a trend towards improved DFS for premenopausal women with EBC who receive T after adjuvant CT. Other studies of similar design have shown improved DFS, but not OS, and meta-analysis may be more informative. Issues affecting results (slow accrual, improved outcomes for EBC, poor compliance, additional therapies) will be discussed. [Table: see text] [Table: see text]