Incidence and mortality rates for colorectal cancer (CRC) in Canada are among the highest in the world. For individuals 50 years and older, CRC screening is effective in reducing both CRC incidence and mortality. The goal of this research was to estimate the extent of CRC screening by conducting a population-based study of tests and procedures used to evaluate the large bowel.

Researchers identified an inception cohort of all Ontario residents aged 50 to 59 years on January 1, 1995, without a previous history of CRC or large-bowel evaluation, by five tests or procedures: fecal occult blood test (FOBT), barium enema, rigid sigmoidoscopy, flexible sigmoidoscopy, and colonoscopy. The individuals were followed to December 31, 2000, for all tests received, and the proportions that received one or more tests or procedures of each type were determined. Data were obtained from: the Ontario Health Insurance Plan (OHIP) database, the Canadian Institute for Health Information-Discharge Abstract Database (CIHI-DAD), and the Registered Persons Database (RPDB).

An inception cohort of 982,443 individuals without prior CRC or large bowel evaluation was identified. The proportion that had at least one test or procedure was less than 10% for each type. The largest proportion (9.3%) had one or more FOBT(s). Classified according to the initial test received, 14.5% had a non-endoscopic test (FOBT, barium enema) and 6% had an endoscopic test (rigid sigmoidoscopy, flexible sigmoidoscopy, colonoscopy). The majority (79.5%) had no test or procedure to evaluate the large bowel.

An extraordinarily low proportion (<20.5%) of screen-eligible 50 to 59 year-old men and women in Ontario were screened for CRC during a 6-year follow-up. Given the high burden of CRC in Canada, a major opportunity exists to improve the health of Canadians by increasing our screening efforts.