ABSTRACT
Objective To investigate whether the mucosal surface volume can be an alternative to the oral cavity volume for predicting grade 3/4 acute oral mucosal toxicity in patients with locally advanced nasopharyngeal carcinoma(LANPC). Methods A total of 92 patients with LANPC who underwent intensity-modulated radiotherapy(IMRT)and concurrent chemotherapy were enrolled in this study. The delineation of the oral mucosa was performed using oral cavity contours(OCC)or mucosal surface contours(MSC). Dosimetric comparisons of toxicity were performed based on the obtained dose-volume histograms(DVHs). The receiver operating characteristic(ROC)curve and logistic regression analysis were used to do statistical analysis of the data obtained from the two different contour methods. Results Both contouring methods showed a significant dose-volume association between oral mucosal exposure and acute oral mucosal toxicity. Logistic regression analysis showed that body weight loss was the independent associated factor for grade 3/4 toxicity in both OCC group and MSC group(P=0.017 and 0.005). And the independent correlation factors for dosimetric parameters in OCC group and MSC group were V30(P=0.003)and V50(P=0.003),respectively. The area under the ROC curve(AUC)of OCC at V30was 0.753(P=0.001)and the AUC of MSC at V50was 0.714(P=0.004). Conclusions DVH analysis of mucosal surface volume can accurately predict grade≥3 oral mucosal toxicity in patients with LANPC who receive IMRT and concurrent chemotherapy. However, OCC is superior to MSC in clinical application.