Clinical significance of IGF1R gene expression in patients with Stage II/III gastric cancer who receive curative surgery and adjuvant chemotherapy with S-1

Purpose Curative resection and adjuvant chemotherapy is the standard treatment for Stage II/III gastric cancer, and S-1 is widely used for adjuvant chemotherapy. The type 1 insulin-like growth factor receptor (IGF1R) is involved in cell proliferation and prevention of apoptosis in many tumors. We evaluated the relative expression of the IGF1R gene to determine whether such expression correlates with outcomes in patients with Stage II/III gastric cancer. Methods We measured the expression levels of the IGF1R gene in specimens of cancer and adjacent normal mucosa obtained from 134 patients with Stage II/III gastric cancer who received curative resection and adjuvant chemotherapy with S-1. We then evaluated whether the IGF1R gene expression levels correlate with clinicopathological characteristics and outcomes. Results IGF1R mRNA expression levels tended to be higher in cancer tissue than in the normal adjacent mucosa (P=0.078). Multivariate analysis showed that high IGF1R gene expression was a significant independent predictor of poor survival in Stage II/III gastric cancer after curative resection and adjuvant chemotherapy with S-1 (HR 3.681, P=0.007). The overall survival rate was significantly lower in patients with high IGF1R gene expression than in those with low expression (P=0.012). Conclusions IGF1R overexpression is considered a useful independent predictor of outcomes in Stage II/III gastric cancer after curative resection and adjuvant chemotherapy with S-1.