CARDIORESPIRATORY FITNESS AND CANCER MORTALITY IN MEN WITH DIABETES

Abstract

Diabetes has been associated with an increase in risk for many cancers, including pancreatic, biliary, and colorectal cancers. Moderate to high cardiorespiratory fitness (CRF) protects against cancer and overall mortalit y in healthy men. However, the effect of CRF on cancer mortality in men with diabetes is unknown. PURPOSE To determine the effect of CRF on cancer mortality in men with diabetes. METHODS Participants were 1992 men with diabetes mellitus, average age 48.7 years (SD 9.3 years), who received a medical examination and a maximal exercise test during 1970 to 1995, with mortality follow-up to December 31, 1996. Four fitness quartiles were created based on treadmill time. Relative risks of mortality were evaluated using proportional hazards models adjusted for age, exam year, history of cancer, and smoking. Linear trends between fitness and mortality were evaluated by including treadmill time as a continuous variable. RESULTS From this cohort, 71 cancer deaths were identified in 29,843 man-years of observation: 6 prostate, 13 respiratory tract, 24 gastrointestinal (6 colon, 9 pancreatic), 11 lymphomas, and 17 other cancers. Risk of cancer mortality was inversely associated with CRF (p for trend < 0.0001). The hazard ratios (HR) for mortality when compared with the highest fitness quartile were: Quartile 1 (HR 6.6; 95% CI 2.3–19.3), Quartile 2 (HR 4.1; 95% CI 1.4–12.0), Quartile 3 (HR 2.2; 95% CI 1.3–3.7). CONCLUSION High levels of CRF were associated with lower risk of cancer mortality in men with diabetes. Supported in part by NIH research grant AG06945.