Although colonoscopic surveillance of patients after removal of adenomas is widely promoted, little is known about colorectal-cancer mortality among these patients.
Using the linkage of the Cancer Registry and the Cause of Death Registry of Norway, Dr Magnus Løberg and colleagues estimated colorectal-cancer mortality among patients who had undergone removal of colorectal adenomas during the period from 1993 through 2007.
Patients were followed through 2011.
The research team calculated standardized incidence-based mortality ratios using rates for the Norwegian population at large for comparison.
Norwegian guidelines recommended colonoscopy after 10 years for patients with high-risk adenomas, and after 5 years for patients with 3 or more adenomas.
The team found that no surveillance was recommended for patients with low-risk adenomas.
|The standardized incidence-based mortality ratio was 0.96 for patients who had had adenomas removed|
|New England Journal of Medicine|
Polyp size and exact number were not available in the registry.
The researchers defined high-risk adenomas as multiple adenomas and adenomas with a villous component or high-grade dysplasia.
The team identified 40,826 patients who had had colorectal adenomas removed.
During a median follow-up of 7 years, 1273 patients were given a diagnosis of colorectal cancer.
A total of 398 deaths from colorectal cancer were expected, and 383 were observed, for a standardized incidence-based mortality ratio of 0.96 among patients who had had adenomas removed.
The researchers noted that colorectal-cancer mortality was increased among patients with high-risk adenomas, but it was reduced among patients with low-risk adenomas.
Dr Løberg's team comments, "After a median of 7.7 years of follow-up, colorectal-cancer mortality was lower among patients who had had low-risk adenomas removed, and moderately higher among those who had had high-risk adenomas removed, as compared with the general population."