Removing Growths Found to Lower Colon Cancer Risk

A long-awaited study provides the first proof that finding and removing precancerous growths can lower the risk of colon cancer--the nation’s second-deadliest malignancy--by 90%, researchers say.

Hunting down these growths, known as polyps, has become a cornerstone of colon cancer prevention in recent years. But until now, evidence that it works has been only circumstantial.

Colon cancer will strike 152,000 Americans this year and 57,000 will die, the American Cancer Society says. It trails only lung cancer as a deadly malignancy.

Colon cancer starts with precancerous growths called adenomatous polyps. Various methods of looking for these growths have become routine parts of physical exams for older Americans.

The tests are performed on the common-sense belief that removing the growths will prevent cancer from developing.

“There has not, until now, been evidence to support that,” said Dr. Sidney J. Winawer, the study’s principal author. “We have provided evidence that now makes that belief a fact.”

Winawer, a researcher at Memorial Sloan-Kettering Cancer Center in New York, conducted the decade-long National Polyp Study with physicians at six other U.S. hospitals. The results are published in today’s New England Journal of Medicine.

The study was conducted on 1,418 men and women who had had at least one adenomatous polyp removed sometime during 1980 to 1990. They were then given follow-up exams, called colonoscopies, for an average of six years.

During that time, colon cancer was discovered in five people. The tumors were relatively small and had not produced any cancer symptoms. The researchers calculated that if the polyps had not been removed, they would have found about 45 cancer cases during this period.