GASTROENTEROLOGY
LITERATURE ALERT!
LANDMARK ARTICLE - Required reading
Lieberman DA, Weiss DG. One-time screening for colorectal cancer with combined rectal occult-blood testing and examination of the distal colon. N Engl J Med 2001;345:555-60
Detsky AS. Screening for colon cancer – Can we afford colonoscopy? (Editorial) N Engl J Med 2001;345:607-08
Major Findings
-- 2885 subjects age 50-75 (mean 63 years) were subjected to 3 stool samples for fecal occult testing (with rehydration) and then underwent colonoscopy, regardless of the occult blood results.
-- Sigmoidoscopy was defined as an examination of the rectum and sigmoid colon during colonoscopy. Lesions found in this area were presumed to have been found during sigmoidoscopy.
-- Advanced neoplasia was defined as polyps >1cm in diameter, a villous adenoma, a polyp with high grade dysplasia or invasive cancer.
-- Of the 2885 subjects, 45.7% had no polyps. In 16.4%, polyps were hyperplastic or non-adenomatous. In 27.3% polyps were <10mm and classified as “non-advanced”. In 10.6%, advanced neoplasia was found, 24 of these had invasive cancer.
-- Among those with advanced neoplasia, 24% had positive occult blood in stool. (sensitivity of 35%, false positive rate of 6.2%). There was a strong association between the number of positive cards and the finding of advanced neoplasia.
-- Among those with advanced neoplasia, 70% had a positive sigmoidoscopy
-- Combined occult blood testing + sigmoidoscopy will detect advanced neoplasia in 75.8% of subjects and fail to detect neoplasia in 24%
FACTS TO REMEMBER FOR BOARDS
- Rehydration of stool cards increases sensitivity and decreases specificity
- Adding stool hemoccult testing to sigmoidoscopy did not increase the rate of detection of advanced neoplasia, provided all patients with adenomas on sigmoidoscopy underwent a full colonoscopy.
- Doing fecal occult blood testing before sigmoidoscopy saves money, as those patients testing positive go straight to colonoscopy without undergoing sigmoidoscopy
This paper probably overestimates the efficacy of sigmoidoscopy as the patients were prepped for colonoscopy and sedated, increasing the chances of a polyp being found, which would have been missed in a less prepped colon and non sedated patient.
