A team of researchers from the University of Oslo have published a study entitled “Long-Term Colorectal-Cancer Mortality after Adenoma Removal,” in The New England Journal of Medicine, where they demonstrated that patients with precancerous adenomatous intestinal polyps have a lower risk of cancer-related death than previously thought.
Adenomas are benign tumors of epithelial tissue with glandular origin or characteristics that can grow and transform to become malignant.
In the colon, these adenomatous polyps are quite prevalent and are commonly found through colonoscopy.
Usually, they are removed because of their tendency to become malignant, ultimately leading to colon cancer.
Even though colonoscopic surveillance of patients after removal of adenomas is commonly used, there is not much information regarding colorectal-cancer mortality among these patients.
In this recent study, researchers used the Cancer Registry and the Cause of Death Registry of Norway to estimate colorectal-cancer mortality in patients who had undergone removal of colorectal adenomas from 1993 through 2007, following them through 2011. They then calculated standardized incidence-based mortality ratios (SMRs) in this population.
Using the available data, researchers observed that Norwegian guidelines recommended a colonoscopy after 10 years for patients who were at high risk of developing adenomas, and after 5 years for patients with three or more adenomas. However, for patients at a low risk of developing adenomas, no surveillance was recommended. However, polyp size and number were not available in the registry, and the team defined high-risk adenomas as multiple adenomas and adenomas with a villous component or high-grade dysplasia.
Through the information gathered, researchers identified 40,826 patients who had removed colorectal adenomas and found that during a median follow-up of 7.7 years, 1273 patients were given a diagnosis of colorectal cancer.
Moreover, within the 398 deaths expected from colorectal cancer, 383 were confirmed among patients who had surgery from adenoma removal, and colorectal cancer related mortality was increased in patients diagnosed with high-risk adenomas and reduced in patients with low-risk adenomas.
Altogether, these data will hopefully provide a useful information platform that can be used in the clinic by physicians, to understand the relation between adenoma diagnostic and the risk of colorectal cancer development.