FOB tests useful in colon Ca screening

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 two 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 at the Canadian Digestive Disease Week. “And certainly amongst the GI community there was controversy as to whether a screening program based on FOB testing was the best approach.”

To answer this question, they 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.

Reported that a separate group of 2,011 patients underwent 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 adenomas (3.7% diagnostic yield).

“So the yield for those who came with a positive FOBT was significantly higher than all the other routes,” said the 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 had; data were available for 107 patients with positive FOB 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. This suggests that these patients should be triaged for more rapid access to colonoscopy.”