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Cardiorespiratory fitness and risk of cancer incidence and cause-specific mortality following a cancer diagnosis in men: The Cooper Center longitudinal study.
Abstracts that were granted an exception in accordance with ASCO's Conflict of Interest Policy are designated with a caret symbol (^).
Background: Few studies have examined the prognostic importance of cardiorespiratory fitness (CRF) to predict cancer incidence or cause-specific mortality following a cancer diagnosis in men. Accordingly, we examined the relationships between baseline CRF and incidence of prostate, lung, or colorectal cancer in men at Medicare age and subsequent cause-specific mortality among men diagnosed with cancer. Methods: The Cooper Center Longitudinal Study (CCLS) is a prospective observational cohort study of participants undergoing a preventive health examination including CRF assessment at the Cooper Clinic in Dallas, Texas. We studied 17,049 men with a complete CCLS medical exam and cardiovascular risk factor assessment at a mean age of 50± 9 years. Cancer incidence was defined using Medicare claims data. Cox proportional models were used to estimate the risk of adjusted primary cancer incidence and cause-specific mortality after cancer according to baseline age-specific CRF quintiles (Q). Results: The mean times from CRF assessment to cancer incidence and death were 20.2 ± 8.2 years and 24.4 ± 8.5 years, respectively. During this period, 2885 men were diagnosed with prostate, lung, or colorectal cancer and 769 died. Compared with men in lowest CRF quintile, the adjusted hazard ratio (HR) for incident lung, colorectal, and prostate cancer incidence among men in the highest CRF quintile was 0.32 (95% CI: 0.20 to 0.51, p<0.001), 0.62 (95% CI: 0.40 to 0.97, p=0.05), 1.13 (95% CI: 0.97 to 1.33, p=0.14), respectively. In men developing cancer, both cancer-specific mortality and cardiovascular-specific mortality declined across increasing CRF quintiles (p’s <0.001). A 1-MET increase in CRF was associated with a 14% reduction in cancer-specific mortality (HR 0.86, 95% CI: 0.81-0.91, p<0.001), and 23% reduction in cardiovascular-specific mortality (HR 0.77, 95% CI: 0.69-0.85, p<0.001). Conclusions: Fitness is a strong independent predictor of incident lung and colorectal cancer and remained a robust predictor of cause-specific mortality in middle-aged and older men diagnosed with lung, prostate, or colorectal cancer.