Colonoscopy is a commonly used primary or follow-up screening test to detect colorectal cancer (CRC), the second leading cause of death from cancer in the United States. Colonoscopy can reduce the risk of death from CRC through detection of tumors at an earlier, more treatable stage and through removal of precancerous adenomas. Conversely, failure to detect adenomas during colonoscopy may increase the subsequent risk of CRC.
A new multi-center study led by Dr. Douglas A. Corley and colleagues from Kaiser-Permanente of Northern California (with co-investigators from the University of Pennsylvania and Memorial Sloan-Kettering) and published in the current New England Journal of Medicine evaluated colonoscopy findings and long-term outcomes among over 300,000 procedures between 1998 and 2010. The tests were performed by 136 different endoscopists/gastroenterologists, and the goal was to determine if the rate of detection of a colon polyp either a benign adenoma or an adenocarcinoma (CRC) differed significantly among the different providers, and to what extent the detection ability related to eventual outcomes.
As the authors put it:
The adenoma detection rate, the proportion of screening colonoscopies performed by a physician that detect at least one...confirmed colorectal adenoma or adenocarcinoma, has been recommended as a quality benchmark by specialty societies....Currently, professional societies recommend adenoma detection rates of 15% or higher for female patients and 25% or higher for male patients as indicators of adequate colonoscopy quality, although data are lacking to validate these thresholds.
The results confirm the utility of detection rate for CRC or its precursors as a prognostic factor for later development of aggressive or lethal cancers. The study found that over the 10-year-plus follow-up period, 255 advanced-stage CRCs and 147 CRC-related deaths occurred. More to the point, they found that the occurrence/incidence of such dangerous or lethal CRCs was inversely related to the fraction of colonoscopy procedures which detected an abnormality. The incidence rates of CRCs/deaths per 10,000 person-years of follow-up varied from 9.8 in the quintile with the lowest rate of detection, to 4.8 among patients of doctors in the highest quintile of detection.
Again, we ll let the authors conclusion speak for itself, as we cannot make it much clearer:
In a large community-based U.S. population across multiple medical centers, physicians' adenoma detection rates were inversely related to the risk of interval colorectal cancer, including advanced-stage cancer and fatal interval colorectal cancer, among patients with up to 10 years of follow-up. This association was approximately linear across quintiles of adenoma detection rates in our population and was observed for male and female patients, cancers in the proximal and distal colon, and early and delayed interval cancers. These findings support the validity of the adenoma detection rate as a quality measure of physicians' performance of colonoscopy in community practice.
ACSH's Dr. Gil Ross had this comment: "Sadly, there is really no way for the typical patient you and I to maximize our chances of having acolonoscopy done by a 'high-detector' vs. a doctor with a lower success rate. Perhaps someday, re-certification of colonoscopists will require a high-enough standard of pre-malignant and cancerous polyp detection and removal, or even better, a high long-term 'free of disease' rate among their post-procedure follow-ups."