Characteristics of Postpolypectomy Colorectal Cancer Events and Deaths.

Abstract

Postpolypectomy colorectal cancers (PPCRCs) are diagnosed after a cancer-negative colonoscopy with polypectomy. Analyzing PPCRC characteristics informs prevention and early detection strategies. We investigated interval types and etiologies of PPCRCs using World Endoscopy Organization guidelines. PPCRCs were identified in a retrospective cohort of US Veterans who underwent colonoscopy with polypectomy from 1999 to 2016. We classified PPCRCs into interval, noninterval type A, and noninterval type B, defined as cancers diagnosed before, at, and after next recommended surveillance examination, respectively. A root cause analysis was conducted to determine the most plausible etiology. We identified 396 PPCRC events and 90 PPCRC deaths over a median follow-up of 3.9 and 4.2 years, respectively. Among PPCRC events, 55% (95% confidence interval [CI] 50%-60%) were interval, 12% (95% CI 9%-15%) noninterval type A, and 33% (95% CI 29%-38%) noninterval type B. Interval cancers were more likely to be diagnosed at stage 4 than noninterval cancers (16% interval vs 2.1% noninterval type A, 8.3% noninterval type B, P = 0.003). Most interval cancers were due to possible missed lesions with adequate examinations (60%, 95% CI 53%-66%), whereas most noninterval cancers were likely new CRCs (type A: 48%, 95% CI 34%-62%; type B: 84%, 95% CI 77%-90%). Similar results were found for PPCRC deaths. Most PPCRC events and deaths were diagnosed before the next recommended examination, largely because of procedural factors, underscoring the need to optimize quality of baseline colonoscopy and polypectomy. Many PPCRCs were diagnosed after recommended examination, suggesting the need to improve patient adherence to recommended surveillance intervals.