For the first time, a new study has shown that removing polyps by colonoscopy not only prevents colorectal cancer from developing, but also prevents deaths from the disease. Patients in the study were evaluated for up to 23 years after having the procedure, providing the longest follow-up results to date. The collaborative study, led by Memorial Sloan Kettering researchers, was published in the February 23 issue of the New England Journal of Medicine.
“Our findings provide strong reassurance that there is a long-term benefit to removing these polyps and support continued recommendations of screening colonoscopy in people age 50 and older,” says Memorial Sloan Kettering biostatistician Ann G. Zauber, the study’s lead author.
Tumor-like growths called adenomatous polyps are the most common abnormality found during colonoscopy screening and have the potential to become cancerous. Previous research from these investigators showed that removal of polyps prevented colorectal cancer but it was not known whether the cancers prevented were potentially lethal.
This study assessed whether removal of adenomatous polyps reduced colorectal cancer mortality — a finding indicating that the polyps removed had the potential to cause cancer death.
Researchers evaluated 2,602 patients enrolled in the National Polyp Study (or NPS, the largest study of its kind) who had precancerous polyps removed during colonoscopy. The detection and removal of these polyps resulted in a 53 percent reduction in colorectal cancer mortality compared to that of the deaths expected in the general population of comparable size, age, and gender.
Furthermore, patients who had adenomatous polyps removed also had the same low death rate from colorectal cancer for up to ten years after the procedure compared to a control group of people with no polyps.
“The magnitude of reduction in mortality we observed is likely due to high-quality colonoscopy performed by well-trained, experienced gastroenterologists,” says the study’s senior author Sidney J. Winawer, a gastroenterologist at Memorial Sloan Kettering and principal investigator of the NPS.
“Randomized, controlled trials of screening colonoscopy in the general population under way in the United States and Europe will in ten to 15 years provide further evidence for this potentially powerful cancer prevention approach,” adds Dr. Winawer, who is credited with introducing colonoscopy into guidelines for colorectal cancer screening.
In a front-page story in The New York Times print edition on February 23, Dr. Zauber comments: “Not all adenomas become cancers, and not all cancers cause death.” But in many cases, she says, “we have gotten those that would have had the potential to go on and cause a cancer death.”