Prediagnostic lifestyle factors and survival after colon and rectal cancer diagnosis in the National Institutes of Health (NIH)-AARP Diet and Health Study

BACKGROUND Few studies have examined the relationship of lifestyle factors with mortality among patients with colorectal cancer. METHODS Among NIH-AARP Diet and Health study participants, 4213 colon and 1514 rectal cancer cases were identified through linkage to state cancer registries and determined date and cause of death using the National Death Index. Lifestyle factors were assessed at baseline and included: healthy diet (measured by Healthy Eating Index 2005 [HEI-2005]), body mass index (BMI), physical activity, alcohol consumption and smoking. The association of factors was examined individually and combined into a lifestyle score with 5-year mortality from all-causes, colorectal cancer, and cardiovascular disease (CVD). Relative risks (RRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models. RESULTS Among colon cancer survivors, smokers had increased risk of total mortality (RR = 1.74; 95% CI = 1.45-2.08) and colorectal cancer mortality (RR = 1.46; 95% CI = 1.17-1.82), compared to never smokers. Obese (BMI, ≥ 30) individuals had increased risk of all death (RR = 1.19; 95% CI = 1.02-1.39) and CVD death (RR = 1.84; 95% CI = 1.05-3.23), compared to normal weight (BMI, 18.5 to < 25) individuals. Compared to those with the lowest lifestyle score, those with the highest score had a 34% lower risk of all-cause mortality (RR = 0.66; 95% CI = 0.50-0.87). Among rectal cancer survivors, individuals in the highest quintile of HEI-2005 scores had reduced all-cause mortality (RR = 0.60; 95% CI = 0.42-0.86) compared to those in the lowest. Higher combined lifestyle scores were associated with a 46% lower risk of total mortality (0.54; 0.32-0.91). CONCLUSIONS Healthier lifestyle before cancer diagnosis was associated with improved overall survival after diagnosis with colorectal cancer.