Objective This study investigated the predictive value of tumor volume reduction rates(TVRRs) before and after induction chemotherapy in determining the radiosensitivity and prognosis of patients with locally advanced nasopharyngeal carcinomas(NPCs). Methods The clinical data of 172 patients with locally advanced primary NPCs who were treated from January 2009 to December 2012 were collected. Tumor regression was evaluated based on the results of the computed tomography scan or magnetic resonance imaging studies. Data about the tumor diameters before and after induction chemotherapy and after radiotherapy as well as the survival times of the patients were obtained. Results All 172 patients had NPCs. After radiotherapy, the TVRR in patients without residual tumor cells was higher than that in patients with residual tumor cells after induction chemotherapy(median values: 47.7% and 15.1%, respectively), and the 5-year survival rates were 80.3% and 45.6%, respectively. Neck lymph node metastasis was observed in 161 of 172 patients, and the TVRRs were similar(median values: 46.8% in 161 patients without residual tumor cells and 11.1% in 161 patients with residual tumor cells). The 5-year survival rate of the 161 patients without residual tumor cells was 84.5%, and that of patients with residual tumor cells was 37.3%. As shown by the receiver operating characteristic(ROC) curve, the area under the curve(AUC) of the ROC curve for TVRRs in patients with primary NPCs but without residual tumors was 0.851, whereas that for TVRRs in patients with neck lymph node metastasis but without residual tumors was 0.784. This result indicates that TVRR has a high diagnostic performance. The univariate Cox regression analysis showed that clinical stage, TVRR in primary NPCs, neck lymph node metastatic lesions before and after induction chemotherapy, presence or absence of residual tumor cells in primary NPCs, and neck lymph node metastatic lesions after radiotherapy were significantly correlated to overall survival(OS). Results of the multivariate Cox regression analysis showed that clinical stage and presence or absence of residual tumor cells in the lymph nodes after radiotherapy were the independent prognostic factors of OS.Conclusion The TVRR after induction chemotherapy may be an effective predictive indicator of the treatment efficacy of radiotherapy in patients with NPC.
