Purpose: To assess the effect of raloxifene, indicated for osteoporosis treatment and prevention, on invasive breast cancer in subgroups of postmenopausal women defined by risk factors for breast cancer. Experimental Design: Data from the 4-year Multiple Outcomes of Raloxifene Evaluation (MORE) trial (N = 7,705) and a follow-up study, the 4-year Continuing Outcomes Relevant to Evista (CORE) trial (N = 4,011), were analyzed. Prespecified subgroups were defined by age (≥65 versus <65 years), age at menopause (≥49 versus <49 years), body mass index (≥25 versus <25 kg/m2), family history of breast cancer (yes/no), serum estradiol level (5-10 versus <5, >10 versus <5 pmol/L), prior estrogen therapy (yes/no), and bone mass at MORE baseline, and 5-year predicted risk, assessed using the modified Gail model (≥1.67 versus <1.67%), at CORE baseline. Time-to-first invasive breast cancer was analyzed using Cox proportional hazards models. Results: In the placebo group, older age, higher estradiol level, and a family history of breast cancer were associated with an increased breast cancer risk (P < 0.05). Raloxifene therapy was associated with a reduced breast cancer risk in both women at lower and those at higher breast cancer risk. Hazard ratio point estimates were 0.11 to 0.67, corresponding to a 33% to 89% reduction in breast cancer risk with raloxifene versus placebo. The therapy by family history interaction was significant (P = 0.04). Conclusions: Raloxifene therapy was associated with a reduced risk of invasive breast cancer in postmenopausal women irrespective of the presence/absence of risk factors; its effect was greater in women with a family history of breast cancer.
ASJC Scopus subject areas
- Cancer Research