A POSITIVE FECAL OCCULT BLOOD TEST IS A BETTER PREDICTOR OF COLORECTAL CANCER THAN FAMILY HISTO...

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A POSITIVE FECAL OCCULT BLOOD TEST IS A BETTER PREDICTOR OF COLORECTAL CANCER THAN FAMILY HISTORY IN ASYMPTOMATIC PATIENTS

S Jayakumar, J Gregor

University of Western Ontario, London, Ontario
Aims: Colorectal cancer (CRC) is the second leading cause of cancer deaths in Ontario, with approximately 7800 Ontarians diagnosed with CRC annually. It is one of the few cancers that can be prevented (i.e. through the removal of a polyp with malignant potential). In January 2007, Cancer Care Ontario (CCO) launched a program designed to fast track patients for colonoscopy for the purpose of CRC screening. The eligibility requirements designated by CCO for this program were either a positive fecal occult blood test (FOBT) in patients over the age of 50, or a family history of colon cancer in a first degree relative (FHx). Although most patients with CRC manifest symptoms such as hematochezia, anemia, altered bowel habits or pain, a small subset of patients with CRC are asymptomatic. We propose that patients referred for a positive FOBT are more likely to have overt malignancy or high risk polyps than patients referred for a positive FHx.
Methods: A chart review was conducted on patients who had undergone a CCO funded colonoscopy between June 2007 and February 2008. The reason for referral, the presence of symptoms,endoscopic and pathological findings were examined. Both overt malignancies as well as polyps removed were noted. A significant polyp was defined as an adenomatous polyp between 5 and 9 mm, whereas a high risk polyp was defined as a sessile serrated adenoma (SSA), an adenomatous polyp containing high grade dysplasia (HGD), larger than 9 mm, or containing villous architecture.
Results: A total of 1375 patients underwent CCO funded colonoscopy in the above time period. 936 patients were referred for a positive FHx, 250 for a positive FOBT, and 88 for other reasons. 18 overt tumours were found in 16 patients and another 5 patients had malignancies arising within polyps, one of which was a neuroendocrine tumour. Of the 21 patients with malignancy, 2 patients were referred for a positive FHx, whereas 18 were referred for a positive FOBT, and one patient was referred for hematochezia. 8 of the 21 had symptoms, all in the FOBT group. 470 patients (34%) had adenomatous polyps, of which 33% were found to have a total of 178 high risk polyps. Of these 155 patients, 70 were referred for FHx, and 72 for FOBT, 11 for other reasons, and 3 patients had no indication listed.
Conclusions: We examined 1375 patients, and found malignancy in 2% of patients. Of this number, 38% had symptoms suggestive of cancer, and were stratified by the GP through the use of a FOBT. Of the remaining asymptomatic patients with CRC, 77% were referred for a positive FOBT, while only 15% were referred for a positive FHx. Thus, in asymptomatic patients, FOBT has a better yield for CRC than a Hx of CRC in a first degree relative. However, in the setting of high risk polyps, a FHx and FOBT had a similar yield for positive findings.

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