590P - Comparable survival outcome between Thai patients with sporadic young adult and adult onset colorectal cancer

Abstract

BackgroundOverall colorectal cancer (CRC) incidence and mortality are declining due to cancer screening in older patients population, however, the incidence of CRC is increasing in younger adults (<50 years) among several countries, mostly in the United States and Europe. This study aimed to evaluateclinicopathological characteristics of adolescent and young adult (AYA) onset sporadic CRC and outcome in Thai patients. MethodsMedical record of patients who were diagnosed adenocarcinoma of colorectal cancer at Siriraj Hospital between 2007 and 2018 were retrospectively reviewed. The patients were classified into 2 groups: AYA-onset CRC (age 15-39 years) and adult-onset CRC (age >50 years). Associations between sporadic microsatellite stable (MSS) AYA- /adult-onset CRC and clinicaopathological features and outcome were evaluated. ResultsA total 202 patients were diagnosed with AYA-onset CRC with no known history of familial CRC syndromes, 116 had data on mismatch repair status; 94 confirmed MSS CRC. AYA-onset CRC patients were commonly found with left-sided rather than right-sided tumors (77.7% vs 21.8%) and late stage of disease (72.7% in stage III-IV vs 24.7% in stage I-II). Compared with adult-onset CRC (195 patients), AYA-onset MSS CRC had more patients with female gender (p=0.042), signet ring cell/mucinous histology (P=0.039), and perineuralinvasion (P=0.004). On univariate analysis, male gender and mucinous/signet ring cell histology had significantly worse OS (P=0.003 and P=0.016, respectively) and remained significant in multivariate analysis. There was no differences in terms of DFS or OS in both age groups. ConclusionsSporadic MSS AYA-onset CRC in Thai patients was associated with female gender and aggressive pathological characteristics. However, there was no difference in survival outcome between AYA-onset and adult-onset groups. Legal entity responsible for the studyThe authors. FundingSiriraj Research Fund. DisclosureAll authors have declared no conflicts of interest.