Raloxifene and tamoxifen had similar efficacy for preventing invasive breast cancer in women at increased risk.

M e t h o d s Design: Randomized controlled trial. Allocation: Concealed.* Blinding: Blinded (clinicians, participants, and outcome assessors).* Follow-up period: Mean 3.9 years. Setting: Nearly 200 clinical centers in North America. Participants: 19747 postmenopausal women ≥ 35 years of age (mean 59 y, 93% white) whose 5-year predicted breast cancer risk was ≥ 1.66% (mean 4.03%) based on the Gail model. Exclusion criteria included recent use of hormone therapy; history of stroke or venous thromboembolism (VTE); diagnosis of cancer in the previous 5 years; and uncontrolled atrial fibrillation, diabetes, or hypertension. Intervention: Raloxifene, 60 mg/d (n = 9875), or tamoxifen, 20 mg/d (n = 9872), for a maximum 5 years. Outcomes: Invasive breast cancer, noninvasive breast cancer, uterine cancer, uterine hyperplasia, ischemic heart disease, stroke, VTE, osteoporotic fractures, cataracts, and death. Patient follow-up: 99% (intention-to-treat analysis). M a i n r e s u l t s Raloxifene and tamoxifen did not differ for invasive or noninvasive breast cancer, ischemic heart disease, uterine cancer, stroke, fractures, or death (Table). Raloxifene reduced risk for uterine hyperplasia, VTE, and cataracts compared with tamoxifen (Table).