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DIAGNOSTIC YIELD OF COLONOSCOPY IN ONTARIO'S NEWLY LAUNCHED COLORECTAL CANCER (CRC) SCREENING PROGRAM
R Aslahi, W Hopman, P MacDonald, W Paterson
Queen's University, Kingston, Ontario
Aims: In January 2007, the Ontario Ministry of Health and Long Term Care in collaboration with Cancer Care Ontario launched a province-wide CRC screening program for Ontarians based on fecal occult blood (FOB) testing for average risk individuals and colonoscopy for high-risk individuals. The impact of this initiative has yet to be reported. The objectives of the current study were to assess: 1) the diagnostic yield of colonoscopy performed as part of the new Ontario program; 2) the relationship between colonoscopic findings and number of positive FOB tests.
Methods: A retrospective “blinded” chart review of endoscopy procedures performed at Hotel Dieu Hospital, Kingston, Ontario in the first year (April 2007-March 2008) of the new Ontario program was conducted, with a specific focus on colonoscopic and pathologic findings in those with positive family history of CRC in a first degree relative or positive FOB test.
Results: A total of 2775 individuals underwent colonoscopy (mean± SD age 59±14; 50.3% female). 642 cases (23.1%) were referred because of a family history of CRC in a first degree relative and 122 cases (4.4%) were referred for positive FOB tests. For 107 of them, the number of positive tests (out of three) was specified, as follows: 50, 23 and 34 cases had 1, 2, and 3 positive FOB tests, respectively. 659 of the 2775 patients had a pathologic diagnosis of cancer (67) or adenoma (612), of which 170 were diagnosed with high-risk adenoma. (i.e. >1cm, villous component and/or high grade dysplasia). Among those with a history of CRC in a first degree relative 38 (5.9%) cases had high-risk adenomas, and 11 (1.7%) had cancer. This yield was not significantly different between patients whose first degree relative was diagnosed at =< 60 vs. > 60. Of the 107 cases in which the number of FOB tests was specified, there were no cancers detected if only 1 of 3 FOB tests was positive, whereas there were 9 cancers in those where either 2 or 3 of 3 FOB tests were positive. High-risk adenomas were present in 18% of patients with 1 of 3 positive FOB tests and 35% of patients with 2 or 3 positive FOB tests.
Conclusions: Based on the results in our centre, it appears that Ontario's new screening program has been successful in detecting high-risk adenomas/cancer in patients with positive family history of CRC or positive FOB tests. It is suggested screening priority to be given to those with 2 or more positive FOB tests.