Mo1725 ADVANCED AGE IS AN INDEPENDENT RISK FACTOR OF ADVANCED NEOPLASIA RECURRENCE AT COLORECTAL CANCER SURVEILLANCE

Abstract

Introduction: An increasing incidence of colorectal cancer (CRC) in young patients has been well noted. The risk of metachronous advanced neoplasia (AN) in younger patients with CRC in the absence of hereditary syndromes in comparison to older patients is not well defined. Identifying high risk subgroups would provide a customized surveillance strategy which would increase cost-effectiveness. Therefore, this study aims to identify CRC patients at increased risk for metachronous AN for surveillance risk stratification. The primary aim was to compare metachronous AN free survival at any surveillance colonoscopy between patients 50 and >50 while the secondary aim was to evaluate risk factors of metachronous AN. Methods: We retrospectively reviewed colonoscopy and pathology records of patients diagnosed with CRC undergoing curative resection between 2006 and 2016 at 3 medical centers. Exclusion criteria included first surveillance performed at > 3 years, hereditary CRC, IBD, poor bowel prep, total colectomy, and obstructive carcinoma without clearance colonoscopy. Information on race, age, sex, sidedness of cancer, smoking history, aspirin use, and number, size, and histology of adenomas were collected from each patient. Advanced neoplasia was defined as > 10 mm, villous histology, or high-grade dysplasia. Kaplan-Meier curves were used to display time to metachronous AN between groups. Log-rank tests were used to compare the time-to-event endpoint across groups. Risk factors associated with hazard of metachronous AN were evaluated by Cox regression. A two-sided alpha of 0.05 was considered statistically significant. Results: 794 patients were included in analysis with 123 patients 50 and 368 patients 60. The rate of metachronous AN in patients >60 compared to 60 was 13.6% and 9.7%, respectively. The rate of metachronous AN in patients >50 compared to 50 was 12.2% and 7.3%, respectively, while it was 8.6% and 5.7% in first surveillance colonoscopy only. In Kaplan-Meier survival analysis with log-rank test, age >60 (pZ0.03), presence of synchronous adenoma (pZ0.01), and presence of synchronous AN (p<0.0001) were found to be significantly associated with higher recurrence of AN. Age >50 approached significance (pZ0.08). In Cox regression, age >60 was found to be a predictor of metachronous AN (HR 2.12, CI 1.03-4.35) while age >50 was not (HR 1.03, CI 0.36-2.92). Of 17 metachronous CRC, 3 occurred in patients 50 of which 2 had no synchronous AN. Discussion: The risk of metachronous AN in CRC patients is not elevated in patients 50. The risk is significantly higher in older patients >60 at diagnosis. Synchronous AN is also a risk factor for metachronous AN. This study does not support more intensive surveillance in young patients with a diagnosis of CRC.