Adenomas in the Young: What Do They Mean?

Adenomas in the Young: What Do They Mean?

Douglas K. Rex, MD, FASGE, reviewing Enwerem N, et al. Clin Gastroenterol Hepatol 2020 May 16.

The incidence of colorectal cancer (CRC) is increasing in persons under age 50 in much of the world. Endoscopists commonly encounter sporadic adenomas when performing colonoscopy in people under age 50. When these lesions are identified in younger persons, they often raise concerns about the possibility of an inherited mutation driving the early onset of adenoma. Should the patient undergo earlier and more frequent surveillance colonoscopy?

In a review of studies collected over more than 4 decades, and ignoring the autopsy data (autopsy studies typically demonstrate lower adenoma prevalence rates compared to modern colonoscopic studies), the pooled prevalence of adenomas in persons under age 50 years was 10.7%. Increasing age was the clearest risk factor, and male gender increased risk. There were not enough data to adequately assess body mass index (BMI) and smoking status.

The pooled incidence of metachronous advanced neoplasia was 6.0%, though 3 of the 4 relevant studies were from 1 country (South Korea). It was difficult to identify risk factors for metachronous advanced neoplasia. Among 9341 patients undergoing surveillance colonoscopy, only 1 (0.01%) developed metachronous CRC. No study addressed whether surveillance colonoscopy influenced the risk of metachronous CRC.

Douglas K. Rex, MD, FASGE


This detailed analysis shows there are still many unanswered questions about adenomas in people under age 50. Based on these data, the true prevalence (as defined by a modern high-level–detecting colonoscopist using state-of-the-art high-definition instruments) is likely above 20% and strongly age-related. One approach is to consider multigene panel testing when young patients have advanced or multiple adenomas, particularly the younger they are and when they lack other obvious risk factors such as long-term smoking or high BMI.

The key message for clinicians is that in the absence of defined genetic risk, we should not implement more intensive surveillance than recommended in our guidelines simply because a sporadic adenoma is identified in a young person. In cases of uncertainty, I sometimes perform a single surveillance examination at a shorter interval, and if that is negative, return to standard surveillance intervals.

Note to readers: At the time we reviewed this paper, its publisher noted that it was not in final form and that subsequent changes might be made.


Enwerem N, Cho MY, Demb J, et al. Systematic review of prevalence, risk factors, and risk for metachronous advanced neoplasia in patients with young-onset colorectal adenoma. Clin Gastroenterol Hepatol 2020 May 16. (Epub ahead of print) (

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