Background: Early implementation of programmatic colorectal cancer (crc) screening for average-risk individuals 50-74 years of age in Canada has used fecal occult blood tests [fts (guaiac or immunochemical)] and colonoscopy for follow-up of abnormal fts. This paper presents results of an evaluation of this crc screening.
Methods: Five Canadian provincial programs provided aggregated data for individuals with a first-round ft processed between January 1, 2009, and December 31, 2011.
Results: The 104,750 people who successfully completed a first round of screening represented 16.1% of those who had access to the programs between January 1, 2009, and December 31, 2011 (mean age: 61.2 years; men: 61.4 years; women: 61.1 years). Of those participants, 4661 had an abnormal ft (4.4%). Uptake of colonoscopy within 180 days after an abnormal ft was 80.5%, ranging from 67.8% to 89.5% by program. The positive predictive value (ppv) for adenoma was 35.9% for guaiac ft and 50.6% for immunochemical ft. Adenoma and crc detection rates were, respectively, 16.9 and 1.8 per 1000 screened. Of invasive crcs detected, 64.6% were stage i or ii.
Conclusions: Considering the variation in characteristics and stage of implementation of each provincial program, the collaboration of the provinces leading to this report on the early performance of crc screening in Canada is a major milestone. Targets are met or nearly met for significant indicators such as ppv for adenoma and cancer detection rate. Participation is expected to increase as programs are fully implemented in the provinces. Additional effort may be needed to improve timely access to follow-up colonoscopy.
Keywords: Colorectal cancer; average risk; fecal occult blood test; guaiac; immunochemical; screening programs.