Trends, clinicopathological features, surgical treatment patterns and prognoses of early-onset versus late-onset colorectal cancer: A retrospective cohort study on 34067 patients managed from 2000 to 2021 in a Chinese tertiary center

Background: In recent decades, the incidence of early-onset colorectal cancer (EOCRC) has reportedly increased in several developed countries, whereas that of late-onset colorectal cancer (LOCRC) has decreased continuously. The trends, clinicopathological features, surgical treatment patterns, and prognoses of EOCRC and LOCRC in China remain unclear. Materials and methods: This retrospective cohort study was performed in China using data from our pathology registry collected in 2000-2021. Pathologically confirmed cases of colorectal cancer (CRC) were analyzed. The average annual percentage change (AAPC) was estimated to quantify the secular trends. Clinicopathological features, surgical treatment patterns, and prognoses were compared between the two groups. Multivariate Cox regression analyses were performed for disease-free survival and overall survival. Results: A total of 34,067 cases of CRC were included, with 6,369 cases of EOCRC and 27,698 cases of LOCRC. Overall, the numbers of EOCRC (AAPC = 8.4%), LOCRC (AAPC = 11.6%), and CRC (AAPC = 11.0%) cases increased significantly from 2000 to 2021. Compared to the LOCRC group, the EOCRC group had fewer men, comorbidities, concomitant cancers, polyps, and KRAS mutations; more symptoms, rectal cancers, multiple primary CRCs, deficient mismatch repair tumors, poorly differentiated, mucinous adenocarcinoma or signet ring cell carcinoma, advanced TNM stage, vascular invasion, perineural invasion; less laparoscopic surgery and sphincter-preserving surgery; more extended radical resection, perioperative chemoradiotherapy and targeted therapy; and similar disease-free and overall survival rates. Conclusion: The numbers of EOCRC and LOCRC cases have continuously increased over the last two decades. The EOCRC group has more aggressive features, advanced TNM stage, intensified surgical treatment and perioper-ative treatment than the LOCRC group, but similar disease-free and overall survival rates. More CRC screening programs are recommended for younger adults to combat the rapidly increasing trend of EOCRC.