Sigmoidoscopy fails to show precancerous polyps

Sigmoidoscopy, a technique commonly used to check for &to=http:// english.pravda.ru/science/19/94/377/14663_.html ' target=_blank>colon cancer, fails to show precancerous polyps in two-thirds of women tested, according to a study published Wednesday.

Earlier research had already showed a failure rate in men of 30 percent using the technique, which examines the lowest one-fourth of the colon, according to the study financed by the National Cancer Institute.

The study was performed on 1,463 women aged between 50 and 79 years at four US military hospitals.

The more expensive &to=http:// english.pravda.ru/main/2002/07/10/32162.html ' target=_blank>colonoscopy was recommended as a much more reliable test, used for exploratory examinations of the large intestine, and strongly recommended for people aged 50 years and older.

Colon cancer is the second biggest cancer killer in the United States, behind lung cancer, reports the Channel New Asia.

Then the "diagnostic yield" of sigmoidoscopy was calculated by estimating the proportion of patients whose lesions would have been identified if they had that test alone. The lesions were considered detectable if they were found in the parts examined by a sigmoidoscopy.

Then the team compared the findings with results from another study called the Veterans Administration Cooperative Study 380, which evaluated more than 3,000 patients, 97 percent of them men. The VA study had found that fecal occult blood testing (which detects microscopic amounts of blood in the stool) and sigmoidoscopy would identify more than 70 percent of men with advanced polyps.

Not so for women, however, Schoenfeld's team found. While colonoscopy found advanced polyps in 4.9 percent of the women, sigmoidoscopy alone would have found polyps in only 1.7 percent of the women, and missed them in 3.2 percent. Only 35.2 percent of women with advanced polyps would have had their lesions identified if they had undergone just sigmoidoscopy, as compared with 66.3 percent of the men matched for age from the VA study.