Survival Analysis of Metastatic Early-Onset Colorectal Cancer Compared to Metastatic Average-Onset Colorectal Cancer: A SEER Database Analysis.

Simple Summary: Over the last decade, early-onset colorectal cancer incidence has continued to increase. The disparities in outcomes and overall survival (OS) between early-onset colorectal cancer and average-onset colorectal cancer remain controversial. The aim of our study was to compare survival rates and identify potential influential factors affecting outcomes between these two groups. Our results show better overall survival and cancer specific survival in patients with early-onset colorectal cancer which could be contributed to better general health, fewer comorbidities and higher likelihood of receiving aggressive cancer treatments. Background: Early-onset colorectal cancer (EO-CRC) is defined as colorectal cancer diagnosed before the age of 50 years, and its incidence has been increasing over the last decade, now accounting for 10% of all new CRC diagnoses. Average-onset colorectal cancer (AO-CRC) has shown a steady decline in its incidence and related mortality over the past 20 years. The disparities in outcomes and overall survival (OS) between EO-CRC and AO-CRC are controversial. Our study compared OS and cause-specific survival (CSS) between metastatic EO-CRC (mEO-CRC) and metastatic AO-CRC (mAO-CRC) and identified the associated factors. Methods: Data on patient characteristics, tumor characteristics, incidence, and mortality were obtained from the SEER database from 2010 to 2020. We identified 23,278 individuals aged > 18 years with a confirmed diagnosis of all histological subtypes of metastatic CRC (M1 on TNM stage) using ICD-O-3 site codes. mEO-CRC and mAO-CRC were compared. OS distributions and CCS were analyzed using the Kaplan–Meier method and log-rank test to assess differences. A Cox regression model was used to assess the associations between variables. Results: mEO-CRC constituted 17.79% of the cases, whereas 82.21% had mAO-CRC. Most patients with mEO-CRC were 45–49 years old (47.66%), male (52.16%) and White (72.57%) and had adenocarcinoma histology (87.30%). Left colon tumors were most prevalent in both groups (40.26%) but were more prevalent in mEO-CRC patients than in mAO-CRC patients (49.63% vs. 38.23%, p < 0.001). Patients with mEO-CRC had higher OS (p < 0.001) and CSS (p < 0.001) than those with mAO-CRC. Patients with mEO-CRC also had significantly better median overall survival (30 months vs. 18 months, p < 0.001). The factors associated with worse OS included mAO-CRC (p < 0.001), mucinous adenocarcinoma (p < 0.001), male sex (p = 0.003), and a lack of surgical intervention (p < 0.001). Conclusions: Most patients with mEO-CRC fall within the range of 45 to 49 years of age. Patients with mEO-CRC were more likely to receive cancer-directed therapy (including chemotherapy and radiotherapy) and had better OS and CSS than those with mAO-CRC. This is likely attributable to the better performance status, fewer comorbidities, and better tolerance to cancer-directed therapy in mEO-CRC patients. The factors associated with worse OS and CSS were age > 50 years, mucinous adenocarcinoma, male sex, and no surgical treatment. [ABSTRACT FROM AUTHOR]