Polish Study Stratifies Postpolypectomy Surveillance Groups Based on Cancer Incidence and Mortality, Not Advanced Adenomas
Current postpolypectomy surveillance colonoscopy interval recommendations are based on studies using advanced neoplasia as an endpoint, typically defined as cancer or advanced adenomas (adenomas ≥1 cm, high-grade dysplasia [HGD], villous elements, or ≥3 adenomas). A large, Polish screening colonoscopy study has created risk categories using only colorectal cancer incidence and mortality as endpoints.
Between 2000 and 2011, 132 screening centers in Poland performed screening colonoscopy on 265,688 persons (mean age, 56 years; 38% male). The median follow-up was 7.1 years, and the maximum follow-up was 14.4 years. There were 439 cases of colorectal cancer (CRC) and 132 CRC deaths during follow-up.
Recursive partitioning was used to develop the following novel classification system: high risk was adenomas ≥20 mm in size; intermediate risk, adenomas <20 mm with HGD; and low risk, adenomas <20 mm without HGD. In the current stratification system (high risk: adenomas ≥1 cm, HGD, villous elements, or ≥3 adenomas), 63.5% of persons with adenomas are low risk compared to 90% in the novel system.
Compared to the general population, those with no adenomas had a 73% risk reduction in cancer incidence compared to 65% with the current low-risk group, 35% with the current high-risk group, 65% with the novel low-risk group, and no reduction with the novel intermediate-risk group; the group with ≥20-mm adenomas had twice the risk of the general population. Thus, compared to the general population, the current and novel low-risk groups had the same cancer incidence rates. The absolute risk increase in CRC in individuals moved from the current to the new low-risk group was only 6 per 100,000 patients.
Compared to screened individuals with no adenomas, the current and novel low-risk groups had an approximate 50% increase in cancer incidence. The hazard ratio in the novel intermediate- risk group was 3.58, and in the group with ≥20-mm adenomas, the risk increased 9.25-fold. Risk increases for cancer death had comparable magnitude.
Comment:
These are important data because they stratify based on cancer incidence and mortality during follow-up, not advanced adenomas. In the U.S., where adenoma detection rates are often much higher, there might be additional risk stratification possible within the low-risk group, and it’s not clear that U.S. practice and the U.S. medical-legal system would tolerate the absolute risks of postcolonoscopy cancer observed in this study. Nevertheless, these data strongly suggest that expansion of the low-risk adenoma-bearing cohort in the U.S. should be feasible and safe..
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, FASGE
Citation(s):
Wieszczy P, Kaminski MF, Franczyk R, et al. Colorectal cancer incidence and mortality after removal of adenomas during screening colonoscopies. Gastroenterology 2019 Sep 26. (Epub ahead of print) (https://doi.org/10.1053/j.gastro.2019.09.011)
