Beneficial role of customized intraoral stents in radiotherapy for nasopharyngeal carcinoma.

Abstract

e18642 Background: The intraoral stent is a mouth-opening device which may be used in nasopharyngeal carcinoma (NPC) patients during radiotherapy with the intention of preventing unnecessary irradiation in normal adjacent tissue. The purpose of this study was to investigate the effects of individualized intraoral stent on the intensity modulated radiation therapy(IMRT) by evaluation dose distribution and consequent radiobiological derived outcomes for NPC patients. Methods: Sixteen patients with NPC who used intraoral stent and 17 patients without intraoral stent were enrolled in this study. All patients underwent Helical Tomotherapy (HT) in our center. For the planning target volume (PTV), the conformity index (CI) and homogeneity index (HI) were used to compare two groups of HT plans (with or without intraoral stent). The mean dose of normal tissues were recorded for the two groups. Oral mucositis, gustatory sense, mouth opening and salivary function of each patients were weekly assessed at the beginning, during and after radiotherapy by clinical examination. Results: The mean dose metrics of oral cavity, mandible, left and right parotid gland in patients with intraoral stent was significantly decreased by 11.6%, 12.2%, 15.4%, and 8.7% on average, respectively (P < 0.05), while the conformity index (CI, P = 0.056) and homogeneity index (HI, P = 0.676) of the tumor target showed no statistically different. The rates of grade I，II, III of oral mucositis of patients with intraoral stent were 43.15%, 43.75%, 12.50% when radiotherapy was just over. While the rates of patients with intraoral stent were 23.53%, 17.65%, 58.82%. There were significantly different in two groups (p = 0.022). There was no significant difference in the decline of taste function among each groups. But the symptoms of xerostomia and mouth opening restriction in the group with intraoral stent had been relieved significantly compared the group without intraoral stent at 1 month and 6 months after radiation. Conclusions: The custom-made intraoral stents showed promising value at sparing normal tissue during radiotherapy for NPC without affecting target dose coverage or tumor control. Clinical trial information: No. NJSH-2021NL-041.