Consumption of aspartame and risk of breast cancer in the Nurses’ Health Studies

Debate persists regarding the potential carcinogenicity of aspartame, as suggested by experimental studies. Therefore, we prospectively evaluated whether aspartame consumption is associated with breast cancer risk in the Nurses' Health Study (NHS) and NHS II. We used Cox models to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). During nearly 30 years of follow-up, with 4 assessments of intake per year, we documented 10 814 invasive breast cancer cases. Overall, there was no association between aspartame consumption and invasive breast cancer risk (HR per 200 mg/d [approximately one 12-oz serving of diet soda] = 1.00, 95% CI = 0.98 to 1.03). We observed similar lack of associations after excluding cases occurring in the first 10 years of follow-up (n = 3125) (HR per 200 mg/d = 1.00, 95% CI = 0.97 to 1.03). In these cohorts, aspartame consumption did not increase breast cancer risk.