Dose–response effects of aerobic exercise on body composition among colon cancer survivors: a randomised controlled trial

BACKGROUND: Physical activity is associated with a lower risk of disease recurrence among colon cancer survivors. Excess visceral adipose tissue is associated with a higher risk of disease recurrence among colon cancer survivors. The pathways through which physical activity may alter disease outcomes are unknown, but may be mediated by changes in visceral adipose tissue. METHODS: Thirty-nine stage I–III colon cancer survivors were randomised to one of three groups: usual-care control, 150 min wk(−1) of aerobic exercise (low dose) and 300 min wk(−1) of aerobic exercise (high dose) for 6 months. The prespecified key body composition outcome was visceral adipose tissue quantified using dual energy X-ray absorptiometry. RESULTS: Exercise reduced visceral adipose tissue in dose–response fashion (P(trend)=0.008). Compared with the control group, the low- and high-dose exercise groups lost 9.5 cm(2) (95% CI: –22.4, 3.5) and 13.6 cm(2) (95% CI: –27.0, –0.1) in visceral adipose tissue, respectively. Each 60 min wk(−1) increase in exercise predicted a 2.7 cm(2) (95% CI: –5.4, –0.1) reduction in visceral adipose tissue. CONCLUSIONS: Aerobic exercise reduces visceral adipose tissue in dose–response fashion among patients with stage I–III colon cancer. Visceral adipose tissue may be a mechanism through which exercise reduces the risk of disease recurrence among colon cancer survivors.