The Survival Impact of Fluoropyrimidine Metronomic Maintenance Therapy Following Adjuvant Oxaliplatin-based Chemotherapy in Patients with Stage III Colorectal Cancer after Radical Resection: Functional Roles of EGFR as a Potential Predictor

Abstract

Background: This retrospective study evaluate the survival effects of metronomic maintenance therapy with fluoropyrimidine in patients with stage III colorectal cancer (CRC) according to epidermal growth factor receptor (EGFR) expression. Methods: We enrolled 197 patients with stage III CRC who had undergone radical resection and FOLFOX regimen adjuvant chemotherapy. The clinicopathological features and effects of metronomic maintenance therapy on survival according to treatment group and EGFR expression were analyzed. By conducting an in vitro cell line study and in vivo study through knockdout of EGFR gene, we analyzed the capacities of cell proliferation and migration. Results: Postoperative relapse and mortality were significantly more common in the FOLFOX group. Metronomic maintenance therapy was a significantly independent predictive factor of postoperative relapse and mortality, as well as a prognostic factor of disease-free survival and overall survival. We also demonstrated that EGFR-knockout Caco2 cells are more sensitive to the inhibition effect of fluoropyrimidine than the control those. Conclusions: The present study suggested EGFR expression as the prognostic factor in patients with stage III CRC receiving metronomic maintenance therapy. By analyzing EGFR expression and treatment strategies, we can identify the potential candidates with optimal survival benefit from metronomic maintenance therapy in patients with stage III CRC.