Five‐Year Survival Prognosis of Early‐Onset and Later‐Onset Colorectal Cancer by Clinical and Lifestyle Characteristics

BACKGROUND AND AIM: Early-onset colorectal cancer (EOCRC) diagnosed at before 50 years of age has been increasing globally. We conducted a nationwide study to compare the associations of clinical and lifestyle characteristics with 5-year survival between EOCRC and later-onset colorectal cancer (LOCRC) patients. METHODS: We studied 92 365 colorectal cancer (CRC) patients from the Taiwan Cancer Registry diagnosed between 2002 and 2015, with mortality follow-up until 2020. Clinical factors included tumor and treatment characteristics. Lifestyle factors included body mass index (BMI), cigarette smoking, and alcohol consumption. Poisson regression was used to obtain risk ratios and 95% confidence intervals for 5-year overall and CRC-specific survival. RESULTS: EOCRC patients had more advanced cancer staging, less right-sided colon cancer, and less treatment delay of ≥ 30 days than LOCRC patients. EOCRC also had a higher proportion of females and current alcohol or cigarette users. Female sex and treatment delay of < 30 days were significantly associated with improved 5-year overall survival among LOCRC patients but not EOCRC patients. After adjusting for sex and tumor characteristics, EOCRC patients demonstrated slightly better 5-year CRC-specific survival than LOCRC individuals for all CRC sites combined, right-sided colon, left-sided colon, and rectum. Underweight BMI was associated with significantly worse survival only in LOCRC patients. CONCLUSIONS: Our findings of distinct characteristics and prognosis between EOCRC and LOCRC patients contribute to the understanding of CRC by age at diagnosis, which may inform patient surveillance and counseling, as well as promote studies to evaluate age-specific CRC screening and treatment strategies.