Removing precancerous polyps found during a colonoscopy reduces by half a person’s odds of dying from colon cancer, according to study that suggests the tests can be used to help separate patients by risk.
The research, reported Wednesday in the New England Journal of Medicine, followed 2,602 older patients who had precancerous polyps removed during a colonoscopy. Over a median of 15.8 years, the people studied had less than half the number of colon cancer deaths than would have been expected in the general population that age, according to the results.
The finding suggests that an initial screening could be used to separate patients into high-risk and low-risk groups, said Michael Bretthauer, a gastroenterologist who co-wrote an editorial accompanying the study. High-risk patients, those with precancerous polyps, benefited from getting repeated colonoscopies afterwards, he said.
When no precancerous polyps are found in a patient “you can just forget about them, send them home,” said Bretthauer, at Oslo University Hospital Rikshospitalet in Norway, in a telephone interview. “They are at very low risk.”
A colonoscopy is a test in which a doctor slides a tube called a colonoscope into the rectum, allowing the inside of the colon to be viewed with a video camera. Polyps that are found can be removed during the procedure.
While the latest research doesn’t prove colonoscopies saves lives in the general population, it supports colon cancer screening guidelines, said Ann Zauber, a biostatistician at Memorial Sloan-Kettering Cancer Center in New York and the report’s lead author, in a telephone interview.
“We are really reducing colon cancer deaths remarkably,” she said. “It is a very strong effect long term.”
The American Cancer Society recommends that men and women get a colonoscopy or another colon cancer screening test such as fecal occult blood test starting at age 50, according to its website. Colonoscopy should be done every 10 years, it recommends.
The 2,602 patients who got precancerous adenomas removed were 62 on average when they started the study between 1980 and 1990, in an era where colonoscopy was not generally used as a screening exam in the healthy population. The patients were then followed for as long as 23 years.
Through the end of 2003, 1,246 of the patients who had adenomas removed had died. Only 12 of those deaths were from colon cancer, far lower than the 25.4 colon cancer deaths that would have been expected in otherwise similar patients in the general population, according to the study results.
Death rates from colon cancer were very low in a second group of 773 patients who were found to have harmless colon polyps during their colonoscopy. Only 1 of those patients died from colon cancer during the follow-up period.