Investigating the association of WNT pathway dysregulation and young-onset colorectal cancer.

Abstract

217 Background: Colorectal cancer (CRC) is the third most common cancer in the United States with studies showing increasing incidence of Young-Onset CRC, defined as cases occurring in individuals 50 years old or younger. Separately, the WNT Signaling Pathway and its subsequent mutation can result in sustained activation and, therefore, unregulated cell proliferation which has been well described in colorectal cancers. Loss of function in APC, AXIN1, AXIN2, GKS3B, and RNF43 can each act to dysregulate WNT signaling, contributing to cancer development. In this study, we aimed to conduct a comprehensive, molecular evaluation of the WNT signaling pathway in colorectal cancer within age-specific cohorts with onset of CRC at 50 years old or less versus greater than 50 years old. Methods: We used published individual patient-level data of 6286 patients with colorectal cancer (CRC) from the 16 CRC datasets included in the cbioportal database. The WNT pathway alterations, including APC, AXIN1, AXIN2, GKS3B and RNF43 mutations were considered to define the WNT mutant CRC cohort. The presence of WNT alterations according to the age (50 years old or younger vs. over 50 years) were evaluated using Chi-square tests. The association between primary tumor distribution (colon vs. rectal) and age were evaluated across patients with and without WNT pathway alterations. The effect of WNT pathway alterations on the overall survival and survival after the metastatic stage was evaluated with Kaplan-Meier survival curves. A type-I error level of 5% (p<0.05) was considered the threshold limit for statistical significance. Results: A total of 2,630 individuals were identified with relevant clinical and molecular information. When comparing WNT alteration patterns between young-onset CRC (< 50 years old) and CRC in cohort >50 years old, there was no statistically significant difference (p-value .215). Analysis of common individual mutations in APC, AXIN1, AXIN2, GKS3B and RNF43 also showed similar incidences across age groups. However, we identified WNT alterations were significantly more common in rectal cancers compared to colon cancer, being found in 75.9% of rectal cancer cases, regardless of age groups (p-value <0.00001). Additionally, individuals identified to have WNT alterations were found to have improved survival with a median overall survival of of 58.19 months versus a median of 41.72 months in those without. Conclusions: Overall, no significant differences were found in WNT alteration expression between Young-onset CRC versus CRC in individuals over the age of 50. However, across all age groups, WNT alterations were frequently found in rectal cancers. Furthermore, these WNT alterations were associated with better outcomes.