BANFF, ALTA. — A colorectal screening program in Ontario has proven successful in detecting high-risk adenomas and colorectal cancer in patients referred because of positive fecal occult blood test results or a family history of colorectal cancer.
“About 2 years ago, the Ontario Ministry of Health announced this new colorectal screening program, which is based on fecal occult blood [FOB] testing for average-risk patients and colonoscopy for those with a first-degree relative with colorectal cancer,” said Dr. William G. Paterson at the Canadian Digestive Diseases Week. “And certainly amongst the GI community there was controversy as to whether a screening program based on FOB testing was the best approach,” he added.
To answer this question, Dr. Paterson and his colleagues reviewed the charts of 764 patients referred to the program; 122 were referred because of positive FOB tests. Of those, 14 patients were found to have cancer (11.4% diagnostic yield) and 30 had high-risk adenomas (24.6% diagnostic yield).
The remaining 642 patients screened through the program had a family history of colorectal cancer. Eleven cases of cancer (1.7% diagnostic yield) and 37 high-risk adenomas (5.8% diagnostic yield) were found. The yield for this cohort was not statistically different between patients whose first-degree relative was diagnosed at age 60 years or younger, or at older than 60 years of age.
Dr. Paterson reported that a separate group of 2,011 patients underwent screening colonoscopy outside the newly developed program; 135 of them were considered to be of average risk.
Among average-risk patients, one was found to have cancer (0.7% diagnostic yield); five others had high-risk adenoma (3.7% diagnostic yield).
“So the yield for those who came with a positive FOBT was significantly higher than all the other routes,” said Dr. Paterson, chief of gastroenterology at Queen's University in Kingston, Ontario.
Given the potential importance of positive FOB tests, the investigators also analyzed the data according to the number of positive tests a patient had; data were available for 107 patients with positive FOB test results.
Of the 50 patients who had one positive test, none was found to have cancer, and 10 had high-risk adenomas (20% diagnostic yield). By comparison, 9 of the 57 patients (15.8% diagnostic yield) who had two or more positive tests had cancer, and 20 (35.1% diagnostic yield) had high-risk adenomas.
“More than one positive fecal occult blood test is associated with a statistically significantly higher yield of colorectal cancer,” he added. “This suggests that these patients should be triaged for more rapid access to colonoscopy.”
Dr. Paterson disclosed that he has no relevant financial interests to disclose regarding this topic.
CDDW is sponsored by the Canadian Association of Gastroenterology and the Canadian Association for the Study of the Liver.
