Healthier lifestyle associated with lower postmenopausal breast cancer risk across genetic risk groups

A prospective analysis published in JNCI evaluated lifestyle and inherited susceptibility in relation to invasive breast cancer among 22,725 postmenopausal women in the Multiethnic Cohort. Participants self-identified as White, African American, Native Hawaiian, Japanese American, or Latino. Investigators constructed a healthy lifestyle index from diet, alcohol consumption, body mass index, waist circumference, physical activity, and smoking, and assessed effect modification using a 313-variant polygenic risk score (PRS).

Compared with women with low lifestyle scores, those with high scores had a lower breast cancer hazard in multivariable models (HR 0.67; 95% CI 0.57–0.79). Associations were similar in the low-PRS group (HR 0.63; 95% CI 0.48–0.82) and high-PRS group (HR 0.70; 95% CI 0.57–0.85), without evidence of multiplicative interaction (P=0.48). In analyses stratified by race and ethnicity, inverse associations were most evident among White and Japanese American women.

The findings support the relevance of healthy lifestyle counseling across genetic risk groups, but the observational design does not establish causality. Absence of a detected interaction does not prove identical associations across genetic susceptibility levels. Only the abstract was available; follow-up duration, event counts, absolute risks, and detailed adjustment methods were not provided.