How to identify patients who are less likely to have metachronous neoplasms after a colon cancer: A predictive model

Background âPatients with prior colon cancer have increased risk of metachronous colorectal neoplasms; therefore, endoscopic surveillance is indicated. Current recommendations are not risk-stratified. We investigated predictive factors for colorectal neoplasms to build a model to spare colonoscopies for low-risk patients. Methods â This was a multicenter, retrospective study including patients who underwent surgery for colon cancer in 2001âŠ-âŠ2008 (derivation cohort) and 2009âŠ-âŠ2013 (validation cohort). A predictive model for neoplasm occurrence at second surveillance colonoscopy was developed and validated. Results â 421 and 203 patients were included in derivation and validation cohort, respectively. At second surveillance colonoscopy, 112 (26.6âŠ%) and 55 (27.1âŠ%) patients had metachronous neoplasms in derivation and validation groups; three cancers were detected in the latter. History of left-sided colon cancer (OR 1.64, 95âŠ%CI 1.02âŠ-âŠ2.64), ≥âŠ1 advanced adenoma at index colonoscopy (OR 1.90, 95âŠ%CI 1.05âŠ-âŠ3.43), and ≥âŠ1 adenoma at first surveillance colonoscopy (OR 2.06, 95âŠ%CI 1.29âŠ-âŠ3.27) were independently predictive of metachronous colorectal neoplasms at second surveillance colonoscopy. For patients without such risk factors, diagnostic accuracy parameters were: 89.3âŠ% (95âŠ%CI 82.0âŠ%-94.3âŠ%) and 78.2âŠ% (95âŠ%CI 65.0âŠ%-88.2âŠ%) sensitivity, and 28.5âŠ% (95âŠ%CI 23.5âŠ%-33.9âŠ%) and 33.8âŠ% (95âŠ%CI 26.2âŠ%-42.0âŠ%) specificity in derivation and validation group, respectively. No cancer would be missed. Conclusions â Patients with prior left-sided colon cancer or ≥âŠ1 advanced adenoma at index colonoscopy or ≥âŠ1 adenoma at first surveillance colonoscopy had a significantly higher risk of neoplasms at second surveillance colonoscopy; patients without such factors had much lower risk and could safely skip the second surveillance colonoscopy. A prospective, multicenter validation study is needed.