(HealthDay News) – Treatment with selective estrogen receptor modulators (SERMs) is associated with a significant reduction in the incidence of breast cancer, especially for the first five years after treatment, according to research described as the first comprehensive analysis, published online April 30 in The Lancet.
Jack Cuzick, PhD, from the Queen Mary University of London, and colleagues conducted a meta-analysis using data from nine prevention trials to examine the effectiveness of SERMs on the incidence of breast cancer. Data were analyzed for 83,399 women who were followed for a mean of 65 months for a total of 306,617 women-years of follow-up.
The researchers found that there was a significant, 38% reduction overall in the incidence of breast cancer, and that within the first 10 years of follow-up, 42 women needed to be treated to prevent one breast cancer event. In the first five years of follow-up, the reduction was larger than in years 5–10 (hazard ratio, 0.58), but there was no heterogeneity between time periods. With all SERMS, the likelihood of thromboembolic events was significantly increased (odds ratio [OR], 1.73). There was a significant reduction in vertebral fractures (OR, 0.66), while the reduction for non-vertebral fractures was smaller, but still significant (OR, 0.93).
“For all SERMs, incidence of invasive estrogen-positive breast cancer was reduced both during treatment and for ≥5 years after completion,” the authors write. “Similar to other preventive interventions, careful consideration of risks and benefits is needed to identify women who are most likely to benefit from these drugs.”