Predictive biomarkers for the efficacy of concurrent chemoradiotherapy for patients with colorectal cancer

Colorectal cancer is a common gastrointestinal malignancy. Radiation combined with chemotherapy (also known as concurrent chemoradiotherapy or CCRT) is often used prior to surgery for treating severe cases of colorectal cancer. However, responses of individual tumors to CCRT differ. Therefore, in light of the variability in radiation sensitivity among different tumors, identifying the factors that can be applied to predict CCRT efficacy prior to treatment will aid in making decisions regarding an appropriate treatment strategy. In the present study, we used a gene chip to analyze the expression of candidate genes in the tumor cells of colorectal cancer patients prior to and after treatment with CCRT, in order to identify molecular markers that can predict the efficacy of CCRT. First, we selected a total of 15 CCRT candidate genes based on the results of previous studies, which used the microarray method to select CCRT response-related genes that were also related to tumor malignancy. We collected preoperative CCRT tumor tissues from 17 colorectal cancer patients for whom the efficacy of CCRT had already been determined and used gene chips to analyze the expression of CCRT-related genes in the tissues of these patients. We then compared the results for the expression of CCRT-related genes with those for the clinical efficacy of CCRT. Of the 15 candidate genes, five genes (CK-20, ELAVL4, EV12B, TM4SF3, and ATPA2) were upregulated in >29.4% and one gene (MET) was downregulated in 23.5% of the total patients after treatment with CCRT, indicating that these genes may be potential predictive markers for CCRT efficacy.