P501 - Clinical Features and Epidemiological Trends of Very Early Onset Colorectal Cancer Based on SEER 17 and GBD 2021 Data

Purpose/Background: The current consensus is to define of early-onset colorectal cancer (EOCRC) as CRC in patients younger than 50 years old. EOCRC is often characterized by a rapid increase in incidence, distinct biological features, and poorer prognosis. However, the clinical and prognostic characteristics of different EOCRC subgroups have not been fully elucidated

Methods/Interventions: We utilized the Surveillance, Epidemiology, and End Results (SEER) 17 database and the Global Burden of Disease (GBD) 2021 data to analyze clinical, prognostic, and epidemiological differences by dividing EOCRC into Very Early Onset Colorectal Cancer (VEOCRC, ages 15-29) and Mid-Aged Early Onset Colorectal Cancer (MAEOCRC, ages 30-49) over the past 15 years. Statistical analyses included Kaplan-Meier survival analysis, joinpoint regression, average annual percentage change (AAPC) analysis, decomposition analysis.

Results/Outcomes: The VEOCRC group had a significantly higher proportion of mucinous adenocarcinoma/signet ring cell carcinoma (MA/SRCC) (18.1% vs. 8.7%) and more advanced histologic grades III and IV (32.2% vs. 18.9%) compared to MAEOCRC. However, there were no significant pathological differences between MAEOCRC and Late-onset CRC (LOCRC). VEOCRC had a worse prognosis than MAEOCRC, especially at stage III. Moreover, MAEOCRC had the best prognosis among these three groups, whether measured by overall survival (OS) or by cancer-specific survival (CCS). From 2006 to 2021, the age-standardized incidence rate (ASIR) for VEOCRC grew faster than for MAEOCRC globally (AAPC: 0.78 vs. 0.63), notably in high-middle Socio-demographic Index (SDI) countries (AAPC: 2.01 vs. 1.44). Excluding carcinoid tumors, the incidence of VEOCRC in high SDI countries has remained stable over the past 15 years, whereas in high-middle SDI countries, it surpassed high SDI countries as early as 2013, reaching the highest globally. Decomposition analysis revealed that in high-middle SDI countries, epidemiological changes contributed more to the increase in VEOCRC compared to MAEOCRC.

Conclusion/Discussion: VEOCRC and MAEOCRC differ significantly in clinical characteristics, prognosis, and epidemiology, with VEOCRC showing worse pathology and prognosis. In the past 15 years, the global incidence of VEOCRC has risen faster than MAEOCRC, warranting particular attention from policymakers, especially in high-middle SDI countries.

Prognostic Analysis of Kaplan-Meier (KM) between Different CRC Age Groups.
(A) Overall Survival (OS) analysis between different CRC age groups. (B) Cancer-Specific Survival (CSS) analysis between different CRC age groups. (C) CSS analysis at stage I. (D) CSS analysis at stage II. (E) CSS analysis at stage III. (F) CSS analysis at stage IV.
Rates, case numbers and Disability-Adjusted Life Years (DALYs) of Early-Onset Colorectal Cancer (EOCRC) by Sex Globally (2006-2021).
(A) Age-standardized incidence rate (ASIR) and case numbers in Very Early-Onset Colorectal Cancer (VEOCRC). (B) ASIR and case numbers in Middle-Aged Early-Onset Colorectal Cancer (MAEOCRC). (C) Age-standardized death rate (ASMR) and case numbers in VEOCRC. (D) ASMR and case numbers in MAEOCRC. (E) DALYs and age-standardized DALYs rate (ASDR) in VEOCRC. (F) DALYs and ASDR in MAEOCRC.