ERCC1 expression by immunohistochemistry and EGFR mutations in resected non-small cell lung cancer.

Expression of excision repair cross-complementation group 1 (ERCC1) is important for resistance to platinum agents. Mutations of epidermal growth factor receptor (EGFR) are related to the responsiveness to tyrosine kinase inhibitors in non-small cell lung cancer (NSCLC). This study was performed to determine if ERCC1 expression and EGFR are related to the prognosis of resected NSCLC, and to determine if ERCC1 expression and EGFR mutations are related. We used immunohistochemistry (IHC) to evaluate ERCC1 expression in tumors from 130 patients with curatively resected NSCLC. The median H-score was used as a cut-off for ERCC1 IHC. EGFR mutations were analyzed in exons 18, 19 and 21. ERCC1 expression was detected in tumors from 80 patients (61.5%). ERCC1 was expressed more frequently in smokers and in squamous cell carcinomas. Patients with a positive ERCC1 expression survived longer than ERCC1-negative patients (median overall survival 7.6 years for ERCC1-positive vs. 4.0 years for ERCC1-negative, P=0.046). Subsequent multivariate analysis suggested that ERCC1 expression is an independent prognostic marker of longer survival (hazard ratio: 0.598, 95% confidence interval: 0.357-1.001). EGFR mutations were found in 25 patients (19.2%) but did not affect overall survival. Interestingly, EGFR mutations were more frequent in ERCC1-negative tumors (12.5% in ERCC1-positive vs. 30% in ERCC1-negative tumors, P=0.014). In conclusion, ERCC1 expression was identified as a positive prognostic marker in resected NSCLC. In addition, EGFR mutations were more frequently found in ERCC1-negative tumors.