New data suggest that for individuals who do not have an adenoma detected on an index colonoscopy, the risk of developing an advanced neoplasia (AN) and colorectal cancer (CRC) is lower in those who are aged 40-49 years compared with those who are 50-59 years old.
However, there is no difference between the two age groups in detection rates of nonadvanced adenoma (NAA) or advanced adenoma (AA), the same study found.
"The primary goal of this study was to investigate the risk of metachronous AN associated with conventional adenoma detected on the index colonoscopy," explain the authors, led by Gene Ma, MD, Kaiser Permanente Northern California, San Jose, California.
"The lack of good-quality evidence to inform surveillance in the 40-49 year old population has resulted in inconsistent surveillance patterns in clinical practice, leading to variation in the quality of care including both inadequate and excessive colonoscopic surveillance," Ma and colleagues observe.
The findings from this study "expand our understanding of the risk of AN and CRC in younger individuals and suggest that the current multi-society guidelines for surveillance may be applicable for individuals 40-49 years of age," the authors conclude.
The study was published online August 12 in The American Journal of Gastroenterology .
Comparing the Two Age Groups
The study included 2396 individuals between 40 and 49 years of age and 8978 individuals between 50 and 59 years of age.
The colonoscopy was carried out for screening in 40.2% in the younger age group vs 34.8% in the older age group and was prompted by a positive fecal immunochemical test in 3.3% of the younger age group vs 32% of the older age group.
The median follow-up for both age groups was roughly 7 years.
"When comparing the 40-49 years group to the 50-59 years group, index colonoscopy detected no adenoma in 62.9% versus 40.1% (P < .0001); NAA in 25.4% versus 39.0% (P <.001), and AA in 11.6% versus 21.0% (P < .0001), respectively," Ma and colleagues report.
When the two age groups were compared for surveillance colonoscopy, no adenoma was detected in 67% of the younger age group vs 54.7% of the older age group (P < .0001), whereas NAA was detected in 25.4% of the 40- to 49-year-olds vs 38.4% of the 50- to 59-year-olds (P < .0001). AA was detected in 3.5% vs 6.95 (P < .0001) of persons in each of the two age groups, respectively.
AN was detected on surveillance colonoscopy after index colonoscopy in 2.2% of the younger age group and twice that percentage, at 4.4%, in the older age group (P = .0003). On surveillance colonoscopy, NAA was found in 4.6% of the younger age group compared with 7% of the older age group (P = .03), whereas AA was found in 7.9% of the 40- to 49-year-olds compared with 11.7% of the 50- to 59-year-olds (P = .06).
The median time until surveillance colonoscopy was similar in both age groups when either NAA or AA was found on index colonoscopy, the authors note. In addition, the median time until the detection of AN was similar whether NAA or AA was detected on index colonoscopy, they add.
The overall crude cumulative incidence of AN was lower in the younger age group when no adenoma was detected on index colonoscopy (P = .0003) as well as when NAA was detected, which would be consistent with recommendations from current guidelines for surveillance colonoscopy after adenoma detection. However, there was no difference between the two age groups in the overall cumulative incidence of AN when AA was detected on index colonoscopy.
Overall, the risk for metachronous AN in persons aged 40-49 years was lower when no adenoma was detected on index colonoscopy, but there was no difference between the two age groups when NAA or AA was detected again on index colonoscopy. Similarly, those aged 40-49 years of age had a lower risk for AA or CRC when no adenoma was detected on index colonoscopy — but again, there was no difference in the risk for AA or CRC when either NAA or AA was detected on index colonoscopy.
The authors have no conflicts of interest to report.
Am J Gastroenterol. Published online August 12, 2022. Abstract
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Cite this: After Index Colonoscopy, What's the CRC Risk in 40- to 49-Year-Olds vs 50- to 59-Year-Olds? - Medscape - Aug 31, 2022.