Cardiorespiratory Fitness and Incidence of Digestive System Cancers in Men.

Purpose: To assess the association between cardiorespiratory fitness (CRF) and incidence of digestive system cancers (DSCs) in men.

Methods: A prospective cohort of 4,540 men aged 55.2 ± 13.1 years who were free from malignancy at baseline was studied. Exposure was CRF quantified from treadmill exercise testing (individualized ramp protocol) in metabolic equivalents (METs). Incidence of DSCs was the primary outcome, utilizing medical records of any new diagnosed DSC. Cox proportional hazard analyses were conducted adjusting for established cancer risk factors.

Results: Mean CRF was 8.3 ± 3.5 METs. During 13 ± 7.6 years follow up, 250 (5.5%) DSC cases were diagnosed (colorectal = 163, gallbladder = 46, liver = 23, esophagus = 8, pancreas = 7 and other digestive organ cancers = 3). For each 1-MET increase in CRF there were 6% [Hazard Ratio = 0.94, 95% CI (0.91-0.98), p = 0.006], and 9% [Hazard Ratio = 0.91, 95% CI (0.85-0.97), p = 0.006] lower risks of DSC incidence in the total cohort and among men younger than 60 years old, respectively. Additionally, each 1-MET increase in CRF was associated with 9% lower risks of DSC incidence among never and current smokers. CRF was not associated with DSC incidence among men ≥ 60 years old and among former smokers.

Conclusion: Higher CRF was associated with lower risk of DSC incidence in men, particularly in those younger than 60 years, and never and current smokers. These findings suggest that higher CRF has potential preventive benefits against the development of DSCs, although additional large studies are needed. CRF screening and achieving higher levels could serve as a complementary preventive strategy for public health.