Clinicopathological characteristics and prognosis of colorectal mucinous adenocarcinoma in different age groups of patients: A nationwide retrospective study in China

Background The clinicopathological and prognostic features of different age groups of patients with colorectal cancer (CRC) differ greatly. However, the impact of age on the clinicopathological features and prognosis of colorectal mucinous adenocarcinoma (MAC) remains underexplored. Materials and Methods Clinicopathological data of CRC patients who underwent curative surgery and were pathologically diagnosed with MAC across 23 hospitals in China from 2016 to 2021 were collected. Data from MAC patients in the Surveillance, Epidemiology, and End Results (SEER) database were also collected. The clinicopathologic features and prognosis of MAC in patients in different age groups were analysed. Results The clinicopathological features of MAC patients in different age groups significantly differed. In both the SEER cohort and the Chinese cohort, patients > 60 years old were more likely to be female, have larger tumours, and have a lower pathological N category and TNM category (P < 0.05). In the SEER cohort, significant differences were observed in OS among the young, middle-aged, and elderly patient groups (65.2% vs. 70.7% vs. 66.2%, P < 0.01). In the Chinese cohort, the OS rates were similar (82.9% vs. 89.1% vs. 80.0%, P = 0.06). There was no significant difference in DFS among the young, middle-aged, and elderly groups (80.0% vs. 85.6% vs. 79.2%, P = 0.20). Conclusion In the SEER cohort, patients < 60 years old had more cases with advanced TNM stages, more patients with tumours located in the left colon and rectum, and a higher proportion of male patients. The clinicopathological features were similar among the three groups, except that the young population aged 18–40 years had more advanced TNM stages at diagnosis in the Chinese cohort. Patients in the 40–60 years age group had worse OS than those in the > 60 age group. Young MAC patients should receive more attention because of their aggressive features and poor diagnosis.