<b> Introduction:</b> Early-onset colorectal cancer (EOCRC) accounts for approximately 10% of all colorectal cancers (CRCs). EOCRC has a certain hereditary predisposition and distinct clinicopathological and molecular features compared to the traditional average-onset of colorectal cancer (AOCRC). As previous publications have shown, EOCRC has a more advanced TNM stage and a more aggressive tumor histopathology. </br></br> <b> Aim:</b> In this study, we aimed to evaluate the differences and similarities of EOCRC compared to AOCRC based on clinicopathological characteristics. </br></br> <b>Material and methods:</b> Between January 2010 and December 2020, 394 patients with inclusion criteria who were operated on at the 3rd level health center for colorectal cancer were included in the study. Patients were divided into two groups as EOCRC (50 years and under) and AOCRC. Pearson's chi-square test was used to compare categorical variables in independent groups. In addition, logistic regression analysis was performed using the Backward method with the variables whose relationship with the age group was evaluated, with P < 0.100. </br></br> <b>Results:</b> Our final analysis included 80 EOCRC cases and 314 controls. When the EOCRC group was compared with the AOCRC group, there was no statistically significant difference between gender, tumor location, T stage of the tumor, and survival (P = 0.190, P = 0.924, P = 0.165, P = 0.574). However, a statistically significant difference in the N stage, degree of differentiation, lymphovascular invasion (LVI) and perineural invasion (PNI) status, and P-values were: P = 0.006, P = 0.029, P = 0.019, and P = 0.003, respectively. </br></br> <b>Conclusion:</b> EOCRC has more aggressive tumor biology than AOCRC. Our study shows that more advanced N stage, poor differentiation, tumor deposits, LVI, and PNI are seen more frequently in EOCRC.
Keywords: colorectal cancer; early-onset; late-onset colorectal cancer; young adult.