Association of Physical Activity by Type and Intensity With Digestive System Cancer Risk

Abstract

Digestive system cancers (DSCs) include cancers of the digestive tract (mouth, throat, esophagus, stomach, small intestine, colorectum) and cancers of digestive accessory organs (pancreas, gallbladder, liver). While individual DSCs are etiologically heterogeneous, accumulating evidence suggests the potential presence of common carcinogenic pathways underlying DSCs. The most substantiated is the proinflammatory pathway mediated by cyclooxygenase (COX)-2 enzyme. For instance, a functional polymorphism in the COX-2 gene was associated with an increased risk of DSCs, in particular.¹ Furthermore, observational studies and randomized clinical trials consistently observed that aspirin, which inhibits COX-2, was notably protective against DSCs.^2,3 Thus, factors that affect the COX-2 pathway may modify the risk of overall DSC. One potential candidate is physical activity (PA), which is shown to reduce the COX-2 proinflammatory pathway.⁴ In addition, the benefit of PA on colorectal cancer survival was confined to COX-2–positive cancers.⁵