Clinicopathological patterns and survival outcomes of colorectal cancer among young adults in Malaysia: an institutional cohort study.

<bold>Introduction: </bold>This study aimed to investigate the clinicopathological patterns and survival outcomes of patients with young-onset colorectal cancer (CRC) in Malaysia.<bold>Methods: </bold>A total of 206 patients with young-onset CRC (age < 50 years at diagnosis) and 1,715 patients with late-onset CRC (age ≥ 50 years at diagnosis) diagnosed during 2002-2016 were included. The clinicopathological characteristics of patients with young-onset CRC were compared with those of patients with late-onset CRC during 2009-2013. Kaplan-Meier survival analysis was performed to determine the overall survival (OS) and disease-specific survival (DSS) in these patients.<bold>Results: </bold>The overall proportion of young-onset CRC was 10.7%. The mean age for young-onset CRC was 39.5 ± 7.4 years, with a male-to-female ratio of 1.2:1. There were more Malay patients with young-onset CRC than late-onset CRC (44.0% vs. 19.9%, p = 0.004). Most CRCs were diagnosed at an advanced stage in both groups. However, young-onset CRC showed more aggressive tumour characteristics, such as poorer differentiation and mucinous subtype. Despite such differences, the OS and DSS in both groups were similar (five-year OS for young-onset CRC vs. late-onset CRC: 44.2% vs. 49.0%, p = 0.40; five-year DSS for young-onset CRC vs. late-onset CRC: 48.8% vs. 57.6%, p = 0.53; mean survival of young-onset CRC vs. late-onset CRC: 4.9 years vs. 5.4 years, p = 0.15). Advanced stage at diagnosis and the treatment modality used were independent prognostic factors.<bold>Conclusion: </bold>The unique ethnic and histological differences between patients with young- and late-onset CRC suggest that young-onset CRC may represent a distinct entity. However, despite such differences, both groups were equivalent. [ABSTRACT FROM AUTHOR]