Cardiorespiratory fitness and incident lung and colorectal cancer in men and women: Results from the Henry Ford Exercise Testing (FIT) cohort

Background To the authors' knowledge, the relationship between cardiorespiratory fitness (CRF) and lung and colorectal cancer outcomes is not well established. Methods A retrospective cohort study was performed of 49,143 consecutive patients who underwent clinician-referred exercise stress testing from 1991 through 2009. The patients ranged in age from 40 to 70 years, were without cancer, and were treated within the Henry Ford Health System in Detroit, Michigan. CRF, measured in metabolic equivalents of task (METs), was categorized as <6 (reference), 6 to 9, 10 to 11, and >= 12. Incident cancer was obtained through linkage to the cancer registry and all-cause mortality from the National Death Index. Results Participants had a mean age of 54 +/- 8 years. Approximately 46% were female, 64% were white, 29% were black, and 1% were Hispanic. The median follow-up was 7.7 years. Cox proportional hazard models, adjusted for age, race, sex, body mass index, smoking history, and diabetes, found that those in the highest fitness category (METs >= 12) had a 77% decreased risk of lung cancer (hazard ratio [HR], 0.23; 95% CI, 0.14-0.36) and a 61% decreased risk of incident colorectal cancer (HR, 0.39; 95% CI, 0.23-0.66; with additional adjustment for aspirin and statin use). Among those diagnosed with lung and colorectal cancer, those with high fitness had a decreased risk of subsequent death of 44% and 89%, respectively (HR, 0.56 [95% CI, 0.32-1.00] and HR, 0.11 [95% CI, 0.03-0.37], respectively). Conclusions In what to the authors' knowledge is the largest study performed to date, higher CRF was associated with a lower risk of incident lung and colorectal cancer in men and women and a lower risk of all-cause mortality among those diagnosed with lung or colorectal cancer.