Determinants of Colectomy in Young Colorectal Cancer Patients Age ≤50: A Statewide, Populationbased Study

Abstract

Introduction: Hereditary colorectal cancer (CRC), including Lynch Syndrome (LS) and polyposis syndromes, and Inflammatory Bowel Disease (IBD) may underlie CRC development in approximately 25% of young patients. Colectomy is recommended in these high-risk cases, and considered in young patients in general, as more limited resection may lead to metachronous CRC. As there are no population-based studies examining operative practices in young patients, we analyzed statewide Louisiana Tumor Registry (LTR) data to quantitate colectomy rates in those age ≤50 and assess predictors of more extensive surgery. Methods: Utilizing LTR data supplemented with data from a Centers for Disease Control and Preventionfunded Comparative Effectiveness Research project, we analyzed all patients ≤50 diagnosed with CRC in Louisiana in 2011 (surgical care extending into 2012). Operative type predictors evaluated included socio-demographics, tumor characteristics and healthcare facility type where surgery took place. Results: Of 2427 all-age, statewide CRC patients, 274 were ≤50. 234 underwent surgery at 53 unique facilities (table 1-baseline characteristics, age stratified). 6.8% (16/234) underwent colectomy. Colectomy predictors (table 2) included age ≤45, polyposis (>10 adenomas) (p < .0001), synchronous/metachronous LS-associated cancer (p < .0001) and IBD (p < .0241). Abnormal microsatellite instability (MSI), gender, race, health insurance status and healthcare facility type were not associated with colectomy. Conclusion: The low colectomy rate of 6.8% (ideally ≥25% based on historical hereditary CRC and IBD estimates in young patients) indicates a substantial number of those undergoing limited resection may be at risk for metachronous CRC. Obvious high-risk features including polyposis, IBD or synchronous/metachronous LS-associated cancers drive colectomy performance. Patients with abnormal MSI (LS risk) rarely undergo colectomy. We previously demonstrated a low MSI testing rate of 23% in this 2011 statewide CRC cohort and that MSI results were available pre-operatively in only 16.9% of cases (Karlitz et al, ACG meeting 2014 and Am J Gastroenterol. 2015 Jan 20. doi: 10.1038). These may be contributing factors to the low colectomy rate as failure to identify patients at risk for LS preoperatively and overall will prevent germline genetic testing, which can aid in surgical management decisions regarding resection extent. Young patients with presumed sporadic CRC do not undergo colectomy.Table 1: Descriptive Characteristics of Louisiana Residents Age ≤50 Diagnosed with Colorectal Cancer in 2011, Stratified by Age