Adenoma detection tracks ongoing risk of colorectal cancer

by Thomas R. Collins – A retrospective study of over 224,000 patients who underwent over 314,000 colonoscopies indicates that pre-cancerous adenoma detection tracks the future risk of colorectal cancer. The study was published on April 2, 2014 in NEJM/The New England Journal of Medicine.

“We found that higher levels of detection were associated with a decreased subsequent risk of cancer,” said investigator Douglas A. Corley, MD, PhD, a gastroenterologist and research scientist with the Kaiser Permanente Division of Research in San Francisco. “Taking out adenomas prevents cancers, and early detection likely prevents many cancers.”

The researchers of the study, the largest ever conducted on the subject and the first done in the United States, analyzed data on colonoscopies performed on Kaiser Permanente patients between Jan. 1, 1998, and Dec. 31, 2010, all in Northern California.

Subjects were 50 years or older and each had at least 6 months of follow-up. Each gastroenterologist  had completed at least 300 colonoscopies, performing an average of 2,150 colonoscopies per year.

From 264,972 colonoscopies evaluated, 712 subjects were subsequently diagnosed with a colorectal cancer, after up to 10 years follow-up. There were 255 advanced-stage cancers and 147 deaths.

The investigators reported that for each 1 percent increase in adenoma detection, there was a corresponding 3 percent decrease in colorectal cancer risk.

Dr. Corley added, “Given these results, to maximize the effectiveness of our screening programs, we have been providing feedback to physicians for three years as well as developing new methods to maximize detection rates.”

This research was supported in part by a grant from the National (US) Cancer Institute.