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.
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 (>or=65 versusor=49 versusor=25 versus10 versusor=1.67 versus<1.67%), at CORE baseline. Time-to-first invasive breast cancer was analyzed using Cox proportional hazards models.
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).
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
