A predictive model identifies patients less likely to have adenomas after a colon cancer

Aims. Patients with prior colorectal cancer (CRC) are at slightly increased risk of metachronous colorectal neoplasms, therefore endoscopic surveillance is indicated. Current recommendations of repeating examinations at 1, 3 and 5 years after surgery, are not tailored according to risk stratification. Our aim was to find predictive factors of colorectal neoplasms to build a predictive model, to spare colonoscopies for low-risk patients. Methods. Multicenter retrospective study including patients with colon carcinoma surgically resected from 2001 to 2008 (training cohort) and from 2009 to 2013 (validation cohort). A predictive model for neoplasms occurrence at second surveillance colonoscopy was developed and externally validated. Results 396 and 131 patients were included in training and validation cohort, respectively. Patients with ≥1 adenoma at 2nd surveillance colonoscopy were 113/396 (28.5%) and 21/131 (16.5%) in the two groups. In validation cohort, 3 cancers were found. Four variables identified the low-risk patient's profile of developing metachronous colorectal adenomas: age ≤65 years old, right colectomy, no advanced adenoma at basal colonoscopy and no adenoma at first surveillance colonoscopy. The predictive model showed fair discrimination, with an area under the ROC curve of 0.69 and 0.64, in training and validation cohort. In validation group, If patients with a low-risk profile skip the 2nd surveillance colonoscopy, 25/131 (19.1%) exams would be saved while missing 2/21 (9.5%) patients with ≥1 adenoma; no advanced adenoma nor cancer would be missed. Conclusions We provided a risk-stratification tool for adenoma occurrence after colon surgery, which could prove cost-effective to select patients who could skip the second surveillance colonoscopy.