Epidemiology and early detection of colorectal cancer

Further information consolidating the roles of dietary fat and fiber and physical inactivity in colorectal carcinogenesis has been published in the year under review. A large cohort study identified animal fat as the most important dietary risk factor, and a meta-analysis of fiber supported the role particularly of vegetable fiber in protection. An important population-based study in Scandinavia identified age at onset of ulcerative colitis as a factor independent of length of follow-up; risk at 35 years after onset was 40% for those with early-stage onset. An update at the St. Mark's Hospital, London, surveillance experience offers measured support for endoscopic screening for dysplasia and curable cancer. A unique paper from Japan defines a relative risk of cancer after polypectomy of 2.3. A case-control study of occult blood screening showed that the sensitivity of guaiac testing for fecal occult blood (Hemoccult, Smith Kline Diagnostics, CA) for asymptomatic colorectal cancer is just under 50%. Cost-benefit modeling suggests that annual occult blood testing and 3- to 5-yearly flexible sigmoidoscopy are optimal.