Prognostic Differences Between Early-Onset and Late-Onset Colorectal Cancer.

: Early-onset colorectal cancer (EO-CRC) has become a significant public health concern due to its alarming rise in incidence and the poor prognosis associated with this disease. The aim of our study was to identify epidemiological, clinical, and paraclinical characteristics that could explain the more aggressive evolution of EO-CRC compared to late-onset colorectal cancer (LO-CRC). : We conducted a retrospective study over a two-year period, including 204 patients diagnosed with colorectal cancer (CRC). The patients were divided into two subgroups: those with EO-CRC and those with LO-CRC. Statistical analysis was performed using IBM SPSS Statistics, Version 29.0. : EO-CRC was identified in 11.3% of the patients included in the study. Compared to LO-CRC patients, EO-CRC patients exhibited a tendency for more distal tumor localization and a stenotic endoscopic appearance (43.5% vs. 29.3%). Regarding histopathological diagnosis, EO-CRC patients demonstrated a higher proportion of the mucinous histologic subtype (34.8% vs. 14.4%) and a significantly greater percentage of poorly differentiated tumors (39.1% vs. 14.5%; = 0.010). Immunohistochemical results, available for a limited number of patients, revealed higher CDX2 positivity in LO-CRC patients ( = 0.012) and higher HER2 positivity in EO-CRC patients ( = 0.002). Smoking ( = 0.006) and hypertension ( = 0.002) were more prevalent in EO-CRC patients than in LO-CRC patients. : Patients with EO-CRC exhibit distinct histopathological and molecular characteristics compared to those with LO-CRC, which may contribute to their poorer prognoses. The higher prevalence of the mucinous histological subtype, poor tumor differentiation, increased HER2 expression, and reduced CDX2 expression suggest potential molecular pathways driving the aggressive nature of EO-CRC. These findings highlight the need for tailored screening strategies and personalized therapeutic approaches in younger CRC patients. Future studies should further investigate the underlying mechanisms and potential biomarkers that could guide early diagnoses and targeted treatments.