Predictive Value of ERCC1 mRNA Level from Receiver-Operator Characteristic and Pretreatment EBV-DNA Virus Load in Stage II Nasopharyngeal Carcinoma Patients Receiving Intensity-Modulated Radiotherapy with Concurrent Cisplatin

Background: The molecular mechanisms underlying chemoresistance are still poorly understood in nasopharyngeal cancer; the protein expression of ERCC1 in DNA repair genes has been reported related to resistance platinum and predicting treatment outcomes in various malignant carcinomas, but the benefit for predicting outcomes with optimal cutoff value of ERCC1mRNA is controversial. The level of plasma Epstein-Barr virus (EBV) DNA is positively correlated with clinical stages of nasopharyngeal carcinoma (NPC). The predictive value of ERCC1mRNA from receiver-operator characteristic (ROC) and EBV-DNA level for stratified treatment with stage II NPC is exactly unclear. This study aims to assess the predictive value of combined EBV-DNA and ERCC1 in stage II nasopharyngeal cancer (NPC) patients treated with intensity-modulated radiotherapy (IMRT) with concurrent cisplatin, and provide guidance for future stratified treatment. Methods: A total of 86 stage II NPC patients who received IMRT and concurrent cisplatin-based chemotherapy with or without cisplatin-based adjuvant chemotherapy had measurements of ERCC1 mRNA, and pretreatment EBV-DNA levels were analyzed by real-time PCR (RT-PCR). Associations of ERCC1 mRNA and pretreatment EBV-DNA levels with clinical characteristics and survivals were evaluated. Results: Cutoff value of ERCC1 mRNA obtained from ROC curve was used, and there were significant differences in progression-free survival (PFS) and overall survival (OS) and overall response rate (ORR) between high expression group and low expression group (p = 0.021 and 0.030 and 0.000, respectively). Patients with pretreatment EBV-DNA <2000 copies/mL had significantly better PFS and ORR (p = 0.024 and 0.043, respectively) and a marginally significant impact on OS (p = 0.062) than those with pretreatment EBV-DNA >= 2000 copies/mL. Patients were divided into three groups by combination of ERCC1 mRNA and EBV-DNA level: ERCC1 mRNA low expression/pre-EBV-DNA <2000 copies/mL, ERCC1 mRNA low expression/pre-EBV-DNA >= 2000 copies/mL, and ERCC1 mRNA high expression/pre-EBV-DNA >= 2000 copies/mL. There were significant differences in ORR among the three groups (p = 0.005). The median follow-up was 62 months (range 22-84) with a follow-up rate of 90.70%. In these groups by combination of ERCC1 mRNA and EBV-DNA level, 1, 3, 5-year OS were 100%, 100%, 100%; 100%, 94.1%, 90.9%; and 100%, 85%, 72.9%, respectively (p = 0.038); 1, 3, 5-year PFS were 100%, 100%, 100%; 97.1%, 91.2%, 84.8%; and 95%, 85%, 71.4%, respectively (p = 0.028). Multivariate analysis showed that combination of ERCC1 mRNA and EBV-DNA levels remained independent prognostic factor but not ERCC1 mRNA and EBV-DNA alone. Conclusions: Combined ERCC1 mRNA and pre-EBV-DNA is a better prognostic biomarker in stage II NPC patients treated with concurrent chemoradiation. Patients with ERCC1 mRNA high expression/pre-EBV-DNA >= 2000 copies/mL may benefit from more aggressive treatment.