Genetic Testing for Everyone With 10 or More Adenomas? It’s Low Yield
Douglas K. Rex, MD, MASGE, reviewing Carballal S, et al. Endoscopy 2021 Oct. 4.
Germline genetic testing for inherited colorectal cancer syndromes often is recommended in patients with ≥10 cumulative adenomas. However, the evidence to support this recommendation is very limited.
In a Spanish study of fecal immunochemical testing (FIT) among 9582 FIT-positive participants, 215 (2.2%) had ≥10 adenomas. Germline genetic testing performed in 60 individuals with ≥20 adenomas was positive in 2 patients (3.3%), one with an MUTYH mutation and 52 adenomas and another with an APC mutation and >70 adenomas.
Of 161 patients with at least one surveillance colonoscopy, 32% had an advanced neoplasm at follow-up, and most of these occurred at the first follow-up. The 3-year risk of cancer was 1%.
COMMENTThese investigators did not perform genetic testing on participants with 10 to 19 adenomas, but the yield was low, even for ≥20 adenomas. Previous studies have also suggested a low yield of genetic testing in patients with 10 to 19 adenomas and were more subject to referral bias than the current study. These data suggest that the recommendation to perform genetic testing in persons with ≥10 adenomas should be modified, perhaps after more data can define a higher yield group based on patient age, family history, and smoking history.
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.
CITATION(S)
Carballal S, Sánchez A, Moreira L, et al. Prevalence of adenomatous polyposis in a fecal immunochemical test-based colorectal cancer screening program and risk of advanced neoplasia during follow-up. Endoscopy 2021 Oct 4. (Epub ahead of print) (https://doi.org/10.1055/a-1660-5353)
