title: Intensity-modulated radiotherapy for nasopharyngeal carcinoma: the reduction of radiation-induced trismus.
abstract: The purpose of this study was to evaluate the degree of radiation-induced trismus after intensity-modulated radiotherapy (IMRT) in patients with nasopharyngeal carcinoma (NPC). From 2003 to 2004, 17 non-metastatic NPC patients treated with parotid-sparing IMRT were enrolled. The maximal interincisal distance (MID) was measured to represent the maximum mouth opening. All 17 patients had both pre- and post-IMRT measurements taken, and the normalized MID (post-IMRT MID/pre-IMRT MID) was analysed to evaluate the percentage decrease in MID after IMRT. The median follow-up time was 20.5 months. One patient had nodal failure and was successfully salvaged with radiotherapy. All 17 patients were alive without cancer at the last follow-up. The average MID before IMRT was 46.2 mm (standard deviation (SD), 8.6 mm). The average MID at 12 months post-IMRT was 45.4 mm (SD, 8.9 mm). The averages of normalized MID were 94% (SD, 3.9%) at 5 months post-IMRT and 98.1% (SD, 4.2%) at 12 months post-IMRT. Based on the satisfactory preservation of normalized MID (average of 98.1% at 12 months post-IMRT), we demonstrate that IMRT reduces radiation-induced trismus in NPC patients. The recovery of normalized MID exists in the period from 5-12 months post-IMRT.
authors.affiliation: Department of Radiation Oncology, Chang Bing Show Chwan Memorial Hospital, Taiwan, Republic of China. hsiungcy@hotmail.com
authors.forename: C-Y
authors.initials: CY
authors.lastname: Hsiung
authors.forename: E-Y
authors.initials: EY
authors.lastname: Huang
authors.forename: H-M
authors.initials: HM
authors.lastname: Ting
authors.forename: H-Y
authors.initials: HY
authors.lastname: Huang
mesh_terms: D000328:Adult; D002277:Carcinoma / Q000532:radiotherapy*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D009367:Neoplasm Staging; D011832:Radiation Injuries / Q000517:prevention & control*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*; D016896:Treatment Outcome; D014313:Trismus / Q000209:etiology / Q000517:prevention & control*