SAN DIEGO — Polypectomy can reduce the incidence of and mortality from colorectal cancer, the second-leading cause of cancer death worldwide.
A study in Clinical Gastroenterology & Hepatology pointed out that current surveillance recommendations recommend close follow-up for individuals with higher-risk findings, such as advanced adenoma or large serrated polyp. Less aggressive follow-up — or return to average-risk screening – is advised for those with low-risk findings, such as 1–2 nonadvanced adenomas <10 mm in size based on risk for metachronous CRC and high-risk neoplasia.1
Yet, according to VA San Diego Healthcare System-led researchers, despite widespread implementation, several clinical and research gaps suggest the need for improved postpolypectomy surveillance. Also participating in the study were VA Salt Lake City, UT, Healthcare System; the VA San Francisco Healthcare System and the VA HSR&D Center for Clinical Management Research in Ann Arbor, MI, as well as related academic institutions.
“Current risk stratification for postpolypectomy surveillance is imprecise. Sensitivity and specificity of polyp surveillance guidelines for correctly identifying individuals who ultimately develop metachronous advanced neoplasia are estimated to be 59%–81% and 43%–58%, respectively,” the authors wrote, “As a result, following current surveillance guidelines results in both undersurveillance of some patients who will have high-risk findings on follow-up and oversurveillance of some patients who will not develop high-risk findings.”
The study pointed out that while undersurveillance results in missed opportunities for cancer prevention, oversurveillance can result in exposure to unnecessary colonoscopy-associated risks and burdens and also be costly.
One problem described by the researchers is that existing risk stratification strategies “do not account for influence of baseline colonoscopy quality on risk for subsequent neoplasia, or influence of clinical factors beyond the number, size, and histology of polyps removed. The adenoma detection rate (ADR) of the colonoscopist performing baseline colonoscopy is of particular interest, as it has been well established to be inversely associated with risk for incident and fatal CRC after normal colonoscopy and, in one study, with risk for incident CRC after polypectomy.”
They advised that incorporating ADR into risk stratification models could improve the identification of individuals at low and high risk for metachronous advanced neoplasia.
The study team sought to assess the association of ADR with metachronous advanced neoplasia and create a prediction model for postpolypectomy risk stratification incorporating ADR and other clinical factors.
To do that, the researchers conducted a retrospective cohort study of individuals with baseline polypectomy and subsequent surveillance colonoscopy from 2004 to 2016 within the VA’s healthcare system. Considered for the model were clinical factors, polyp findings, and baseline colonoscopist ADR, The model’s performance (sensitivity, specificity, and area under the curve) for identifying individuals with metachronous advanced neoplasia (MAN) was compared with 2020 U.S. Multi-Society Task Force on Colorectal Cancer (USMSTF) surveillance recommendations.
For the study, 30,897 veterans were randomly assigned 2:1 into independent model training and validation sets. The researchers determined that increasing age, male sex, diabetes, current smoking, adenoma number, polyp location, adenoma ≥10 mm or with tubulovillous/villous features, and decreasing colonoscopist ADR were all independently associated with MAN. “A range of 1.48- to 1.66-fold increased risk for MAN was observed for ADR in the lowest 3 quintiles (ADR <19.7%-39.3%) vs the highest quintile (ADR >47.0%),” they wrote. “When the final model selected based on the training set was applied to the validation set, improved sensitivity and specificity over 2020 USMSTF risk stratification were achieved (P = .001), with an area under the curve of 0.62 (95% confidence interval, 0.60-0.64).”
The study concluded that colonoscopist ADR is associated with MAN, adding, “Combining clinical factors and ADR for risk stratification has potential to improve postpolypectomy risk stratification. Improving ADR is likely to improve postpolypectomy outcomes.”
Background information in the article argued that current risk stratification relying on only the number, size, and histology of polyps detected is imprecise, “resulting in both undersurveillance of individuals at increased risk for metachronous advanced neoplasia, and oversurveillance of individuals at low risk for metachronous advanced neoplasia”.
The authors concluded, “We demonstrated that a prediction model using additional patient characteristics, as well as colonoscopist ADR, can improve prediction at cutoffs selected to improve sensitivity or specificity by at least 10 percentage points relative to USMSTF recommendations. As such, this work fills gaps in evidence to support use of factors beyond the number, size, and histology of polyps for risk stratification; supports the concept that colonoscopy quality influences outcomes after polypectomy; and emphasizes the potential benefit of using new approaches for risk stratification of individuals who have had polypectomy.”
The researchers also noted that, because of the large national sample, “our findings of a consistent association between age, male sex, adenoma number, adenoma size, tubulovillous/villous features, diabetes, and smoking help highlight the significance of these features for risk stratification.”
- Gupta S, Earles A, Bustamante R, Patterson OV, et. al. Adenoma Detection Rate and Clinical Characteristics Influence Advanced Neoplasia Risk After Colorectal Polypectomy. Clin Gastroenterol Hepatol. 2023 Jul;21(7):1924-1936.e9. doi: 10.1016/j.cgh.2022.10.003. Epub 2022 Oct 19. PMID: 36270618.