Clinicopathologic Features and Prognostic Factors in Alpha-Fetoprotein-Producing Colorectal Cancer: Analysis of 78 Cases

Abstract

Background/Aims: Alpha-fetoprotein-producing colorectal cancer (AFPP-CRC) is quite rarely seen. This study aimed to elucidate the clinicopathologic characteristics and prognostic factors of AFPP-CRC. Methods: Among 5,051 colorectal cancer patients receiving surgery in the Fudan University Shanghai Cancer Center from 2006 to 2016, we identified 78 patients with elevated serum level of AFP (> 10 µg/L) preoperatively. A propensity score matching (PSM) analysis was performed which matched 75 AFPP-CRC patients to the same number of AFP-negative colorectal cancer (AFPN-CRC) patients. Kaplan-Meier curves were compared using the log-rank test and multivariable analysis was performed to evaluate the effect of AFP-positivity while adjusting confounding factors. 27 patients were available for immunohistochemical analysis. We conducted functional experiments to characterize the tumorigenicity of AFP. Results: Patients with AFPP-CRC had a significantly higher incidence of advanced TNM stage and liver metastasis. Overall survival was significantly different between two groups before and after PSM, and AFP-positivity was one of the strongest predictors of overall survival in the multivariable model (HR 4.11, CI 95%: 1.43-11.76, p = 0.009) after PSM. We further investigated prognostic factors affecting prognosis in AFPP-CRC and found that the presence of liver metastasis was the only independent prognostic factor (HR 4.95, CI 95%: 1.48-16.48, p = 0.009). AFP expression was significantly positively correlated with HGF and c-Met expression. Transwell invasion assay revealed significantly increased cell motility with AFP overexpression. Conclusion: AFP-positivity is a significant negative predictor of overall survival in patients with colorectal cancer, which may be mediated by HGF/c-Met signaling pathway.