BACKGROUND AND OBJECTIVE: The incidence of early-onset colorectal cancer among the young (<
50 years) has been reported to have risen in last decades. This retrospective study aimed to investigate the characteristics of early-onset rectal cancers (EO-RCs) and potential changes in proportion of EO-RCs, and further to report the mortality and recurrence rates of EO-RCs. METHODS: In the years 2007-2021, 2557 rectal cancer (RC) patients were operated in Helsinki University Hospital and of them 147 were 18-49 years old. Cumulative overall survival (OS), disease-specific survival, and disease-free survival were calculated using the Kaplan-Meier analysis. RESULTS: The percentual amount of the EO-RCs varied between 2.5% and 11.3% annually and there was no perceivable trend. Majority were adenocarcinomas (98.7%), of which 8.8% were mucinous. Predisposing factors such as Lynch syndrome, polyposis, or ulcerative colitis were seen in 26 patients (17.7%) and in 10 of 22 patients (45.5%) under 35 years. The cumulative 5-year OS was 91.9% in stage I, 93.3% in stage II, 86.7% in stage III, and 50.0% in stage IV disease. Metastatic recurrence was found in 22 cases (18.4%) and local recurrence in 8 patients (5.4%) and 6 patients had both. CONCLUSIONS: In our cohort of 147 EO-RC patients, OS was good and the clinical course did not seem to differ much from the course of RC in general population.