Large Pedunculated Adenomas Without High-Grade Dysplasia Did Not Increase Subsequent CRC Risk in FIT-Positive Patients
Douglas K. Rex, MD, MASGE, reviewing Zorzi M, et al. Clin Gastroenterol Hepatol 2024 Feb 5.
Patients with high-risk adenomas (≥10 mm, villous elements, high-grade dysplasia, higher numbers of adenomas) are at higher risk of cancer during surveillance and warrant more intense surveillance. Much of the world relies on fecal immunochemical test (FIT) screening for colorectal cancer (CRC), and FIT-positive patients have a high prevalence of high-risk adenomas.
This Italian study evaluated the risk of CRC following 87,248 colonoscopies in patients after a positive FIT result. The study also followed a control group of FIT-negative patients. The CRC incidence during follow-up in FIT-positive patients with no adenomas at baseline colonoscopy was numerically lower than the risk in FIT-negative patients. The hazard ratio for CRC in FIT-positive patients with low-risk adenomas (one or two small tubular adenomas) at baseline colonoscopy was 1.18 compared with FIT-positive patients with no adenomas—a difference that did not reach significance.
Overall, the high-risk adenoma cohort comprised 26% of the FIT-positive colonoscopy group. Within this high-risk adenoma group, 39.2% had only a distal pedunculated polyp without high-grade dysplasia. This group of patients with a large distal pedunculated adenoma without high-grade dysplasia had a similar risk of subsequent CRC (hazard ratio [HR], 0.87) compared with the FIT-negative group. Among the high-risk group that had proximal location, nonpedunculated morphology, or high-grade dysplasia in the most advanced lesion, there was a clear increase in subsequent CRC risk, which increased sharply as the number of these factors increased (HR, 1.49, 2.24, and 4.15 for one, two, and 3 risk factors, respectively).
COMMENT
Because FIT best detects bleeding from distal sources, FIT-positive colonoscopy patients have a high prevalence of large distal pedunculated polyps. This study indicates that if colonoscopy shows a large pedunculated distal polyp with no high-grade dysplasia and the patient has few additional or no findings, the patient may belong in a low-risk surveillance group, which could reduce the surveillance burden for FIT-based CRC screening programs.
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.
Douglas K. Rex, MD, MASGE
CITATION
Zorzi M, Battagello J, Barbiellini Amidei C, et al. Low colorectal cancer risk after resection of high-risk pedunculated polyps. Clin Gastroenterol Hepatol 2024 Feb 5. (Epub ahead of print) (https://doi.org/10.1016/j.cgh.2024.01.027)
COMMENT
This study affirms important principles for FIT screening. First, cancers detected by FIT remain in an early stage during subsequent screening rounds. Further, increasing the cutoff level of hemoglobin for positive test results reduces sensitivity but does not shift the fraction of detected cancers substantially toward later-stage CRC. Thus, programs can adjust the cutoff to levels appropriate for their colonoscopy resources, and the detected cancers will be in an early stage across a range of hemoglobin thresholds for positive tests.