Higher adenoma detection rates (ADR) during colonoscopies were associated with lower rates of interim colorectal cancer (CRC), and the relationship held true along a broad range of ADR values, according to a retrospective study.
The new study, published online in JAMA, examined ADRs and rates of interim colorectal cancer among patients in California and Washington State between 2011 and 2017. The authors found a 3% reduction in risk for each additional 1% value of ADR. The reduction in risk held true even at high ADRs.
“It basically reaffirms what we’ve believed for the longest time, and other research work has documented – that interim cancers are higher in association with lower adenoma detection rates. The higher you can get that adenoma detection rate, the more we’re going to be able to lower the [rate of] cancers that develop within 3 years of a colonoscopy,” said Lawrence Kosinski, MD, who was asked to comment on the study.
The study included 735,396 patients with a median age of 61.4 years. Among these patients, 852,624 negative colonoscopies were performed by 383 eligible physicians. Participating physicians had to perform at least 25 screening colonoscopies and 100 total colonoscopies per year. After 2.4 million person-years of follow-up, the researchers observed 619 postcolonoscopy colorectal cancers and 36 related deaths over a median follow-up of 3.25 years.
There was an association between each 1% increase in ADR and a reduced probability of postcolonoscopy CRC (hazard ratio [HR], 0.97; 95% confidence interval [CI], 0.96-0.98) and mortality from postcolonoscopy CRC (HR, 0.95; 95% CI, 0.92-0.99).
The median ADR was 28.3%. There was an association between ADR above the median versus below the median and a reduced risk of postcolonoscopy CRC with 1.79 cases versus 3.10 cases per 10,000 person-years, respectively (absolute difference in 7-year risk, –12.2 per 10,000 negative colonoscopies; HR, 0.61; 95% CI, 0.52-0.73). There was a similar reduction in risk of postcolonoscopy CRC-related mortality (0.05 versus 0.22 per 10,000 person-years; absolute difference in 7-year risk, –1.2 per 10,000 negative colonoscopies; HR, 0.26; 95% CI, 0.11-0.65).
These findings may be limited in generalizability to physicians with lower procedure volumes or to populations with different adenoma prevalence.
“Given the strong, consistent associations of higher adenoma detection rates with colonoscopy effectiveness for reducing colorectal cancer incidence and mortality, the current results support more research to identify reliable and readily adoptable methods for increasing adenoma detection rates among physicians with lower values across diverse settings,” the researchers wrote.
The improvement over a broad range of ADRs, along with other recent findings, suggests that there may need to be updates to the use of ADRs as a quality metric, according to an accompanying editorial by Douglas K. Rex, MD, of the division of gastroenterology/hepatology at Indiana University, Indianapolis. For example, it’s possible that ADRs could be measured by averaging values from screening, diagnostic, and surveillance colonoscopy. The editorialist suggested that, if improvements in interim cancer rates continue as ADRs approach 50%, the current view of ADRs, as a minimally acceptable standard, may require reconsideration. Instead, it may be appropriate to continue with a minimum threshold, but add a much higher, aspirational target. Dr. Rex also suggested that highly-variable detection of sessile serrated lesions could be excluded from ADRs in order to reduce variability.