Adulthood overweight exerts lifelong effect on breast, colorectal cancer survival

The duration and degree of overweight in adulthood appear to have lasting influence on breast and colorectal cancer survival, a study has found.

Researchers looked at a cohort of 47,051 women from the Swedish Lifestyle and Health Study and estimated trajectories of body mass index (BMI) between ages 20 and 50 years using a quadratic growth model.

In the cohort, 1,241 women developed postmenopausal breast cancer (mean age at diagnosis, 57.5 years) and 259 colorectal cancer (mean age at diagnosis, 59.1 years).

Multivariate Cox regression models revealed that relative to never having been overweight (BMI <25 kg/m²) during early adulthood, every year lived with overweight increased the risk of early death from breast cancer by 3 percent (hazard ratio [HR], 1.03, 95 percent CI, 1.01–1.05) and from colorectal cancer by 4 percent (HR, 1.04, 1.01–1.06). Greater overweight intensity (defined as a combination of duration and degree of overweight—a concept comparable to pack-years of cigarette smoking) further increased the risk of mortality.

Risk estimates were slightly more pronounced in women diagnosed with late-stage breast cancer but not colorectal cancer.

The findings point to the need for effective prevention of overweight and obesity starting at an early age, according to the researchers.