1142P - To compare two oral mucosa contouring methods in predicting acute oral mucocitis in nasopharyngeal carcinoma treated with helical tomotherapy

Abstract

BackgroundThe purpose of this study was to evaluate prediction effect for acute radiation-induced oral mucositis (A-ROM) of two oral mucosa contouring methods in nasopharyngeal carcinoma (NPC) patients treated with helical tomotherapy. MethodsA total of 151 AJCC 7th stage II-IVB histologically proven NPC patients receiving radical tomotherapy (TOMO) from Zhejiang Cancer Hospital were included. All patients received 0-4 cycles of platinum-based induction chemotherapy±1-3 cycles of concurrent chemotherapy (all patients received at least one chemotherapy). Oral cavity contour (OCC) and mucosa surface contour (MSC) were applied to radiation treatment plans. A-ROM were prospectively assessed weekly according to RTOG scoring criteria. Absolute DVH data was exported from RayStation V3.0 system. T-test, X2 test, binary logistic regression and ROC curve were used to analyses. ResultsMorbidity of≥3 grade A-ROM was 30.4%. In univariate analysis: V10, V15, V45, V55, V60, V65, V70 of OCC and V15, V55, V60, V65, Dmean of MSC were significant related to≥3 grade A-ROM (Vx, percentage volume of organ received more than Gy, all P0.05). In binary logistic regression analysis, gender, smoking were found significantly related to≥3 grade A-ROM by using OCC (male vs. female : OR=0.070, 95%CI=0.019-0.411, P=0.008 ; smoking vs. non-smoking: OR=15.250, 95%CI=4.421-61.980, P=0.001). For MSC, gender, smoking and MSC V55 were independent predictors (male vs. female : OR=0.152, 95%CI=0.037-0.642, P0.001 ; smoking vs. non-smoking: OR=4.028, 95%CI=2.145-32.079, P=0.032 ; MSC-V55 : OR=2.665, 95%CI=1.172-3.365, P0.004). The cutoff of MSC-V55 was 10.38%, area under curve was 0.697, with sensitivity and specificity of 0.635 and 0.704, respectively. ConclusionsWe recommend MSC as a more reasonable method for oral mucosa contouring in TOMO treatment plan for nasopharyngeal carcinoma patients. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.