Review Lifestyle factors and colorectal cancer risk (2): a systematic review and meta-analysis of associations with leisure-time physical activity.
Harriss DJ, Atkinson G, Batterham A, George K, Cable NT, Reilly T, Haboubi N, Renehan AG, Colorectal Cancer, Lifestyle, Exercise And Research Group. Colorectal Dis. 2009 Sep; 11(7):689-701. Epub 2009 Jan 17.