Colonoscopy reduces mortality from colorectal cancer

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 researchers at Memorial Sloan-Kettering Cancer Center, will be published in the February 23, 2012 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 over age 50," said the study's lead author Ann G. Zauber, PhD, a biostatistician at Memorial Sloan-Kettering.

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 these 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 that would indicate that the polyps removed had the potential to progress and cause cancer death.

Researchers evaluated the long-term results of 2,602 patients enrolled in the National Polyp Study (NPS, the largest study of its kind) who had precancerous polyps removed during colonoscopy. They found that the detection and removal of these lesions 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 10 years after the procedure compared to a control group of people in whom no such polyps were detected.

"The magnitude of reduction in mortality seen after this procedure is likely due to high-quality colonoscopy performed by well-trained, experienced gastroenterologists," said the study's senior author Sidney J. Winawer, MD, a gastroenterologist at Memorial Sloan-Kettering and Principal Investigator of the NPS. "Randomized controlled trials of screening colonoscopy in the general population underway in the US and Europe will in 10 to 15 years provide further evidence for this potentially powerful cancer prevention approach," added Dr. Winawer, an internationally recognized leader in the prevention of digestive cancers who is credited with introducing colonoscopy as a key component of national guidelines for colorectal cancer screening in the United States and worldwide.