Colonoscopy is much better that the less expensive screening procedure called sigmoidoscopy to detect cancer of the colon in elderly patients, a new study said.
"We imagined there would be some difference, but there is a quadruple difference" between the two tests when it comes to detect cancer, said Dr.-Yize Richard Wang, researcher at the Mayo Clinic in Jacksonville, Florida, author of study
"Colonoscopy remains still the gold standard," said Wang, a health economist.
To the United States colon cancer kills more than 51 000 people per year, according to the National Cancer Institute. Testing to identify cancer before appear it symptoms, when it may be easier to treat.
Colonoscopy, the most common colon cancer screening test, involves Threading a scope with a tiny camera throughout the colon. But patients can also choose flexible sigmoidoscopy, which uses a shorter scope, less costs and may be more comfortable. However, sigmoidoscopy looks at only half or less of the colon, Wang said.
Years ago sigmoidoscopy was the principal for colon cancer screening, but it has become less frequent over time. However, "from the point of view of patient, preparation and discomfort related to a sigmoidoscopy is often seen as less heavy," said Dr. Thomas Semrad, internal Assistant Professor of medicine at the University of California, Davis Medical Center, who is familiar with the results of the study.
Using a database of national, the authors of the study examined 52,236 67 patients records or older who have had a colonoscopy or sigmoidoscopy between 1998 and 2005 and have been diagnosed cancer of the colon in the three years of the procedure. According to the summary of the study, a 57,412 colonoscopies were performed, and 3,523 sigmoidoscopies.
The percentage of new or missed the left colon cancer was 12% in sigmoidoscopy patients but only 4% for patients for colonoscopy.
It is not clear why colonoscopy was the best in the detection of cancers, Wang said, but it may be because the sigmoidoscopy lack part of the colon.
"If you think that the patient has cancer of the colon, colonoscopy is still a test better than flexible sigmoidoscopy", he said.
Differences in the preparation of the intestine and the lack of sedation may also help explain the variation in, say the authors of the study, noting further research is needed.
The study to be presented Tuesday at Digestive Disease Week Conference in Chicago. Research is considered preliminary because he has not been subjected to the examination required for publication in a refereed journal.
Although the study did not include persons of less than 67, "results may be similar," said Wang.
Said Semrad sigmoidoscopy may be appropriate in some cases. From a colonoscopy, "a sigmoidoscopy individual cost less, be easier to perform, and in the right hands can be an appropriate test," he said.
"Ultimately, the proper test will be different for different patients and different health systems," Semrad added.
The U.S. Preventive Services Task Force recommends screening colonoscopy every 10 years for people aged 50 to 75 years, which are regarded as medium risk of obtaining colon cancer.
It is important that people undertake screening, said Semrad. "We know that we could save thousands of lives each year if everyone threw guidelines", he added.
But some people are afraid of the procedure, he noted. He noted "because the preparation is easier and the malaise is less often, [sigmoidoscopy] may be particularly important tests for patients not be willing to undergo a colonoscopy".
