Exercise reduces the incidence and mortality of colorectal cancers

We identified people from a large prospective cohort study who had been diagnosed with colorectal cancer, at some time after enrolment into the study (all cases were healthy when they entered the study). Data on body size and physical activity was collected on everyone when they joined the cohort (baseline).

What we originally found (published in GUT Jan 2006) was that of those people subsequently diagnosed with colorectal cancer who were regular exercisers at baseline had a better cancer specific survival than non-exersisers.

The current study now attempts to explain why this may happen. All cases also had serum stored at baseline. Levels of insulin-like growth factor 1 (IGF1) and insulin-like growth factor binding protein 3 (IGFBP-3) were measured. IGF1 is a potent growth factor, while IGFBP-3 bind to IGF1 and inhibits its action. For exercisers, but not for non-exercisers, higher levels of IGFBP-3 related to an improved survival IGF1 was not predictive of survival. This may explain in part the mechanism whereby exercise reduces the incidence and mortality of colorectal (and other) cancers.

Bibliographical reference:

Haydon AM et al.: "Physical activity, insulin-like growth factor 1, insulin-like growth factor binding protein 3, and survival from colorectal cancer", Gut. 2006 May;55(5):689-94

Andrew Haydon

Department of Epidemiology and Preventive Medicine, Monash Medical School, Alfred Hospital, Melbourne, Australia