NEJM: Adenoma detection rates may predict interval colorectal cancer

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The adenomatous lesion detection rate is an independent predictor of the risk of interval colorectal cancer after screening colonoscopy, according to the findings of a recent study published in the May edition of the New England Journal of Medicine.

Jaroslaw Regula, MD, of the Department of Gastroenterology at the Institute of Oncology in Warsaw, Poland, and colleagues said that despite rates of adenoma detection and cecal intubation being recommended for use as quality indicators for screening colonoscopy, these measurements have not been validated.

“The primary aim of the study was to assess the association between quality indicators for colonoscopy and the risk of interval cancer,” wrote Regula and colleagues.

Utilizing a multivariate Cox proportional-hazards regression model in order to evaluate the influence of quality indicators for colonoscopy on the risk of interval cancer (colorectal adenocarcinoma that was diagnosed between the time of screening colonoscopy and the scheduled time of surveillance colonoscopy), the researchers gathered data from 186 endoscopists who were involved in a colonoscopy-based colorectal-cancer screening program involving 45,026 patients. By way of the screening program's database and data on interval cancers from cancer registries, the authors acquired quality-indicating data for colonoscopy.

After an average follow-up period of 52.1 months, 42 interval colorectal cancers were identified. Of these cancers, 35 (83.3 percent) occurred in subjects with no family history of colorectal cancer and 39 (92.9 percent) occurred in subjects in whom no adenomas had been identified at the screening examination. The authors wrote that the interval cancer could be attributed to an ineffective polypectomy in one patient (2.4 percent), as the completeness of the polypectomy was undetermined.

“The endoscopist's rate of detection of adenomas was significantly associated with the risk of interval colorectal cancer… The risk was significantly higher among subjects who underwent colonoscopies that were performed by endoscopists with an adenoma detection rate of less than 20 percent than among subjects examined by endoscopists with a detection rate of 20 percent or more, whereas the rate of cecal intubation was not significantly associated with this risk,” said Regula.

Citing age as another factor that was independently associated with the risk of interval colorectal cancer, as risk was found to be particularly high for subjects who were 60 years of age or older, the authors noted that limitations to their study included the fact that there is no universally accepted definition of interval cancer, as well as potentially incomplete cancer registries.

“These results, obtained in a large cohort, underscore the crucial role of meticulous inspection of the colorectal mucosa at the baseline examination and indicate that such inspection is a very important factor in the efficacy of screening,” concluded the researchers.