Fortnightly review: screening for asymptomatic colorectal cancer

Abstract

Colorectal cancer is one of the most common cancers in Western Europe and the United States with more than 300 000 cases a year. Most tumours evolve from normal mucosa to adenomatous polyp to invasive cancer, and survival is directly related to the extent of the disease at operation (fig 1). This strong relation between tumour stage and survival provides a rationale for intervention at an early pathological or premalignant stage. Fig 1 Survival of 777 consecutive patients with colorectal cancer stratified by tumour stage.1 (Data from St Vincent's Hospital colorectal cancer database) Our research interests in gastrointestinal carcinogenesis, cost-benefit analyses of screening, and gastrointestinal endoscopy were helpful in researching and writing this review. The literature on screening for colorectal cancer is extensive, and we were therefore selective in the papers that we reviewed for this article. Our computerised literature search on a medical database (Ovid-Medline, Ovid Technologies, New York, USA)–which used the keywords “colonic neoplasms or rectal neoplasms or colorectal neoplasms” and “mass screening or screening (textword)”–yielded over 1800 matches since 1966. We selected randomised controlled trials when possible, but there are relatively few such studies published on faecal occult blood testing and none on flexible sigmoidoscopy. We also selected well conducted case-control studies, though many of the data are necessarily observational. In addition, we continuously reviewed general medical and gastroenterology journals for the most recent and important articles about screening. #### Summary points The strong relation between the stage of colorectal cancer and survival provides a rationale for screening, but present recommendations are controversial Regular endoscopic screening is recommended for members of families with adenomatous polyposis and of families with hereditary non-polyposis colorectal cancer Subjects with one or two relatives with colorectal cancer should be assessed individually before a decision about colonoscopic screening is made Screening populations at average risk of colorectal …