NEW YORK - A new study provides what independent researchers call the best evidence yet that colonoscopy - perhaps the most unloved cancer screening test - prevents deaths. Although many people have assumed colonoscopy must save lives because it is so often recommended, strong evidence has been lacking until now.
A team of researchers led by Dr. Sidney J. Winawer, a gastroenterologist at Memorial Sloan-Kettering Cancer Center in New York City, followed 2,602 patients for as long as 20 years. In that group, the death rate from colorectal cancer was cut by 53 percent in those who had the test and whose doctors removed precancerous growths, known as adenomatous polyps, the researchers reported yesterday in The New England Journal of Medicine. The test examines the inside of the intestine with a camera-tipped tube.
“For any cancer screening test, reduction of cancer-related mortality is the holy grail,’’ said Dr. Gina Vaccaro, a gastrointestinal oncologist at the Knight Cancer Institute at Oregon Health and Science University who was not involved in the research. “This study does show that mortality is reduced if polyps are removed, and 53 percent is a very robust reduction.’’
Colorectal tumors are a major cause of cancer death in the United States and one of the few cancers that can be prevented with screening. But only about 6 in 10 adults are thought to be up to date on getting screened for colorectal cancer.
Cancer screening tests have come in for greater scrutiny recently. A government panel recommended in October that men no longer get the PSA blood screening test for prostate cancer after concluding it did not save lives. The new study on colonoscopy has limitations - it is not a randomized clinical trial - but some specialists say it nonetheless was well-done and helps answer questions about the effectiveness of the procedure.
Colonoscopy is expensive, costing hundreds or thousands of dollars, depending on whether polyps are removed and on the part of the country where it is done. It also carries small risks of causing bleeding or perforation of the intestine. And it requires sedation and taking strong, usually foul-tasting laxatives to clean out the intestines so that the doctor can look for polyps.
“Any screening is better than none,’’ Winawer said.