Recommendations on screening for colorectal cancer in primary care
340 CMAJ, March 15, 2016, 188(5) (c)2016 8872147 Canada Inc. or its licensors Colorectal cancer is the second most common cause of cancer related death in men and the third most common in women;1 the lifetime probabilities of dying from colorectal cancer among men and women are 3.5% and 3.1% respectively.2 Although the burden of colorectal cancer varies across Canada,3 it is estimated that 25 000 Canadians received a diagnosis of colorectal cancer in 2015 (incidence 49 per 100 000 population) and that 9300 will die from the disease (mortality 17 per 100 000).1 The incidence and mortality of colorectal cancer are low until middle age and rise rapidly thereafter (Figure 1).1,4 Most colorectal cancers appear to arise from colonic polyps that develop slowly and sometimes transform to cancers.5 This is the ration ale for screening programs that aim to reduce deaths due to colorectal cancer by detecting and removing polyps and/or early stage colorectal cancers. Implementation of organized screening programs in some Canadian provinces has been associated with an increase in the number of individuals screened,6 and other provinces are in the process of implementing such programs (Appendix 1, available at www.cmaj.ca/lookup/ suppl/doi:10.1503/cmaj.151125/ /DC1) Currently, all Canadian programs recommend screening with guaiac fecal occult blood testing (gFOBT) or fecal immunochemical testing (FIT) This guideline presents recommendations for screening for colorectal cancer in asymptomatic adults aged 50 years and older who are not at high risk for colorectal cancer, and it updates previous Canadian Task Force on Preventive Health Care recommendations from 2001.7 The 2001 guideline recommended annual or biennial FOBT (grade A recommendation) and flexible sigmoidoscopy every five years (grade B recommendation) in asymptomatic people older than 50 years. The guideline did not recommend whether these screening modalities should be used alone or in combination (grade C),7,8 or whether to include or exclude colonoscopy as an initial screening test for colorectal cancer. Given the major changes in technology and practice since 2001, the guideline has been updated based on the most recent data available to provide guidance for primary care practitioners on different screening tests, screening intervals and recommended ages to start and stop screening.
Canadian Medical Association Journal