Molecular characteristics of early-onset compared with late-onset colorectal cancer: a case controlled study

Abstract

Background: Early-onset colorectal cancer (EOCRC) is associated with a poorer prognosis relative to late-onset colorectal cancer (LOCRC), and its incidence has witnessed a gradual escalation in recent years. This necessitates a comprehensive examination of the underlying pathogenesis and the identification of therapeutic targets specific to EOCRC patients. The present study aimed to delineate the distinct molecular landscape of EOCRC by juxtaposing it with that of LOCRC.

Methods: A total of 11 344 colorectal cancer patients, diagnosed between 2003 and 2022, were enrolled in this study, comprising 578 EOCRC cases and 10 766 LOCRC cases. Next-generation sequencing technology was employed to assess the tumor-related mutation and tumor mutation burden (TMB) in these patients. PD-L1 expression was quantified using immunohistochemistry. Microsatellite instability (MSI) was determined via capillary electrophoresis (2B3D NCI Panel).

Results: Upon comparing LOCRC with EOCRC patients, the latter group demonstrated a tendency towards advanced TNM stage, lower tumor differentiation, and less favorable histological types. Among LOCRC patients, those with MSI-H status were found to have an earlier TNM stage compared to those with MSI-L/MSS status. Significantly, the incidence of MSI-H was notably higher in EOCRC (10.2%) compared to LOCRC (2.2%). Mutations in the 7-gene panel (ARID1A, FANCI, CASP8, DGFRA, DPYD, TSHR, and PRKCI) were more prevalent in LOCRC. Within the EOCRC cohort, patients with the MSI-H subtype displayed an earlier TNM stage but concurrently exhibited poorer tissue differentiation and a higher frequency of mucinous adenocarcinoma. Among EOCRC patients, FBXW7, FAT1, ATM, ARID1A, and KMT2B mutations were significantly enriched in the MSI-H subgroup. A comparative analysis of MSI-H patients revealed heightened mutation frequencies of FGFBR2, PBRM1, RNF43, LRP1B, FBXW7, ATM, and ARID1A in the EOCRC group. Furthermore, EOCRC patients demonstrated a higher overall TMB, particularly in the MSI-H subtype. PD-L1 expression was elevated in EOCRC and positively associated with MSI status.

Conclusions: This study revealed a significantly higher MSI-H distribution rate in EOCRC, and EOCRC exhibits a distinct mutational signature coupled with higher PD-L1 expression. These findings hold promise in guiding personalized therapeutic strategies for improved disease management in EOCRC patients.

Figure 1

Mutation spectrum in all lesions of EOCRC and LOCRC patients. (A) The detailed mutation type in EOCRC patients. (B) The detailed mutation type in LOCRC patients. The frequency of transition (Ti) or transversion (Tv) was compared. (C) The top 20 most frequently mutated genes and tumor mutation burden are shown in the histogram of EOCRC patients. (D) The top 20 most frequently mutated genes and tumor mutation burden in LOCRC patients. The number of mutations is illustrated in the right panel. The types of mutations are colored differentially and labeled. EOCRC, early-onset colorectal cancer; LOCRC, late-onset colorectal cancer.

Figure 2

Mutation landscape difference in EOCRC and LOCRC. (A) The detailed mutation frequency of genes in EOCRC and LOCRC. The types of mutations are colored differentially and labeled. (B) The mutation frequency difference was presented in forest maps with odds ratios (OR). EOCRC, early-onset colorectal cancer; LOCRC, late-onset colorectal cancer.

Figure 3

Mutation landscape difference in EOCRC with different MSI status. (A) The detailed mutation frequency of genes in EOCRC with different MSI status. The types of mutations are colored differentially and labeled. (B) The mutation frequency difference was presented in forest maps with odds ratios (OR). EOCRC, early-onset colorectal cancer; MSI, microsatellite instability; MSI-H, high microsatellite instability.

Figure 4

Somatic mutation in MSI-H EOCRC patients. (A) Mutation spectrum of special somatic mutation in MSI-H EOCRC patients. The frequency was labeled in left. (B) The mutation frequency difference was presented in forest maps with odds ratios (OR). EOCRC, early-onset colorectal cancer; MSI, microsatellite instability; MSI-H, high microsatellite instability.

Figure 5

Tumor mutation burden (TMB) and PD-L1 value among each group of patients with early-onset colorectal cancer and late-onset colorectal cancer. (A) The TMB value of each patient was determined to be the highest TMB value of each lesion of the patient. mut/mB indicates mutations per megabase. B. PD-L1 expression was evaluated using tumor proportion score and combined positive score. * indicated P<0.05; ** indicated P <0.01. MSI, microsatellite instability; MSI-H, high microsatellite instability.

Figure 6

MSI status associated with overall survival (OS) and disease-free survival (DFS) of colorectal cancer patients. (A) Patients were divided into three groups including MSS, MSI-L and MSI-H. The OS and DFS were calculated in EOCRC patients. (B) Patients were divided into three groups including MSS, MSI-L and MSI-H. The overall survival and disease-free survival were calculated in LOCRC patients. EOCRC, early-onset colorectal cancer; LOCRC, late-onset colorectal cancer; MSI, microsatellite instability; MSI-H, high microsatellite instability; MSI-L, low microsatellite instability.