Incidence of Colorectal Cancer After Endoscopic Mucosal Resection: A Multicenter Electronic Health Record Cohort Study

BACKGROUND: Endoscopic mucosal resection (EMR) is widely used for large and complex colorectal lesions and offers a less invasive alternative to surgery. Although adenoma recurrence after EMR has been described in procedural cohorts, real-world estimates of subsequent colorectal cancer (CRC) diagnoses after EMR across multicenter electronic health record (EHR) systems remain limited. METHODS: We conducted a retrospective cohort study using the TriNetX US Collaborative Network. Patients aged 40 years or older who underwent colonoscopy or sigmoidoscopy with EMR between January 1, 2016 and January 1, 2017 were included. Patients with Crohn's disease, ulcerative colitis, familial adenomatous polyposis, or CRC recorded on or before the index EMR date were excluded. The primary outcome was incident CRC, defined by ICD-10-CM codes C18, C19, and C20, assessed from January 1, 2018 through December 31, 2021 after a one-year washout period. Incidence rates are reported per 1,000 person-years with exact Poisson 95% confidence intervals (CIs). A sensitivity analysis was restricted to patients aged 50-75 years at index EMR. RESULTS: Among 3,081 eligible patients, the mean age was 62.9 ± 8.89 years and 52% were female; 2,735 were at risk at the start of follow-up. Twenty-two incident CRC diagnoses occurred over 10,187.8 person-years, an incidence of 2.16 per 1,000 person-years (95% CI, 1.35-3.27). Each calendar year contained 10 or fewer events, so annual rates could not be estimated. Incidence was 2.54 (95% CI, 1.31-4.44) in males and 1.83 (95% CI, 0.88-3.36) in females. In the 50-75-year sensitivity cohort, 19 events occurred over 8,894.8 person-years (2.14 per 1,000 person-years; 95% CI, 1.29-3.34). During years 1-5 after index EMR, repeat EMR occurred in 119 patients (3.9%), colorectal surgery in 28 (0.9%), and subsequent colorectal polyp diagnoses in 1,321 (42.9%); no ESD procedures were identified. CONCLUSION: CRC diagnoses after EMR were uncommon in this multicenter EHR cohort, occurring at about 2 per 1,000 person-years. Event counts were too small to estimate annual trends or to compare incidence reliably across race and ethnicity groups. Studies linking EHR data to endoscopy and pathology reports are needed to identify preventable cancers after EMR.