A new study published online November 8, 2023, in *Menopause*, the journal of The North American Menopause Society (NAMS), found that the drug Lasofoxifene significantly reduced breast density and the risk of invasive breast cancer in postmenopausal women with fewer side effects. This analysis, based on the Phase 3 PEARL trial, which originally enrolled 6,654 postmenopausal women with osteoporosis, suggests Lasofoxifene as a promising option for breast cancer prevention, particularly for women with dense breasts, a known risk factor that also complicates mammography interpretation.
The study focused on 1,189 women from the PEARL trial who had available mammogram data and received either 0.5 mg/day of Lasofoxifene or a placebo for five years. Researchers observed that Lasofoxifene users experienced a 10.9% reduction in breast density, assessed by the Breast Imaging Reporting and Data System (BI-RADS) score, compared to a 1.2% increase in the placebo group (p<0.001). Additionally, the drug demonstrated a 42% reduction in the risk of invasive breast cancer, indicated by a hazard ratio of 0.58 (95% confidence interval, 0.35–0.96).
Compared to other Selective Estrogen Receptor Modulators (SERMs) such as tamoxifen and raloxifene, Lasofoxifene exhibited a more favorable side effect profile, with fewer reports of hot flashes, vaginal dryness, and leg cramps. Rates of deep vein thrombosis and pulmonary embolism were low and similar to those in the placebo group. Dr. JoAnn Pinkerton, executive director of NAMS, stated, 'Lasofoxifene's unique attributes could significantly improve the therapeutic landscape for breast cancer prevention.' While the drug is already approved in Europe for osteoporosis and vaginal atrophy, and in the US for vulvovaginal atrophy and osteoporosis, researchers anticipate it could become a new option for breast cancer prevention, pending further specific trials.
