Weighty Effects on Breast Cancer Outcomes

Obesity raises risk for incident breast cancer; moreover, high body-mass index (BMI) can worsen prognosis. In a report based on data from nationwide clinical trials of adjuvant treatment for early-stage breast cancer conducted since 1977, Danish investigators assessed obesity's effects on risk for breast cancer recurrence and death among almost 19,000 women who received treatment for early-stage breast cancer between 1977 and 2006.

Participants with BMIs ≥30 kg/m² were older and had more-advanced disease at diagnosis than those with BMIs <25. Cumulative incidence of distant metastasis at 10 years was 24% versus 20% (adjusted hazard ratio, 1.46; P=0.007), and cumulative risk for death from breast cancer at 30 years was 57% versus 46% (AHR, 1.38; P=0.003). However, high BMI was not associated with excess risk for locoregional recurrence. Chemotherapy as well as adjuvant endocrine therapy with tamoxifen or an aromatase inhibitor were less effective after 10 years of follow-up in women with BMIs ≥30.