Colonoscopies are among the least popular screening tests. But a new report gives us reason to love them more: They do save lives.
At a time when the effectiveness of some cancer screening tests such as one for prostate cancer are not holding up to scrutiny, the report shows that colonoscopies cut the death rate from colorectal cancer by 53% in patients who had the test and had precancerous growths, called adenomatous polyps, removed by their doctors.
“For any cancer screening test, reduction of cancer-related mortality is the holy grail,” Dr. Gina Vaccaro, a gastrointestinal oncologist at the Knight Cancer Institute at Oregon Health and Science University who was not involved in the research, told The New York Times. “This study does show that mortality is reduced if polyps are removed, and 53 percent is a very robust reduction.”
The research team, led by Dr. Sidney J. Winawer, a gastroenterologist at Memorial Sloan-Kettering Cancer Center in New York City, reported their results on Wednesday in The New England Journal of Medicine.
Study details and caveats
For as long as 23 years, the researchers followed more than 2,600 patients who had precancerous growths called adenomatous polyps removed during colonoscopies from 1980 to 1990.
They then compared the death rate of that group with that of the general population, in which 25.4 deaths from colorectal cancer would have been expected in a group of the same size. But in the group who had their polyps removed, there were only 12 deaths.
While the study is significant, there are also some caveats about the results.
First, study is not a randomized clinical trial, but some experts say it still demonstrated the effectiveness of the procedure. Second, it did not test colonoscopy against other colorectal cancer screening methods, such as looking for blood in the stool or sigmoidoscopy, which examines only the lower part of the colon and is no longer commonly done in the U.S.
The importance of screening
While no one finds any type of colorectal cancer screening pleasant, doctors say the minor discomfort of a test is worth it, because colorectal cancer is one of the few types of cancer in which premalignant growths can been identified and the disease can be prevented if those growths are removed. As the Times reports, "Research indicates that not every polyp turns into cancer, but that nearly every colorectal tumor starts out as an adenomatous polyp."
Colorectal tumors are a major cause of cancer death in the United States, with more than 143,000 new cases and 51,000 deaths expected this year. Only about 6 in 10 adults are up to date on their colorectal cancer screenings, according to federal estimates.
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Chart: In black, deaths from colorectal cancer in the general population. In blue, deaths among the study group observed after removal of adenomatous polyps. Red: The death rate of those in the study group with a different type of polyp. /The New England Journal of Medicine