title: Parotid gland-sparing 3-dimensional conformal radiotherapy results in less severe dry mouth in nasopharyngeal cancer patients: a dosimetric and clinical comparison with conventional radiotherapy.
abstract: OBJECTIVE
  This study examined the efficacy of parotid gland sparing of three-dimensional conformal radiotherapy (3DCRT) compared with conventional radiotherapy for NPC patients. Both the dose given to the parotids and clinical assessment of dry mouth were conducted.
  
  
  METHODS
  Dry mouth was assessed for 108 patients treated with conventional technique and 72 treated with 3DCRT. Dose analysis was performed in 48 patients of the 3DCRT group. A dose of 70 Gy was given to the midplane in conventional radiotherapy and to 90% isodose volume in 3DCRT. Prognostic factors affecting the severity of dry mouth were analyzed using Generalized Estimating Equation (GEE).
  
  
  RESULTS
  In the 3DCRT group about 50% of the patients' parotid glands received less than 25 Gy. Parallel analysis of dry mouth shows a significant decrease in the incidence of severe xerostomia after 3DCRT. The proportion of patients without dry mouth was also significantly higher in the 3DCRT group than the conventional group at 1-3 years after completion of radiotherapy. Although 3DCRT delivered a higher dose to the tumor, it spared the parotid gland significantly better than the conventional treatment. Late toxicities were mostly similar between the 2 groups while local control in T4 patients and survival were improved for 3DCRT.
  
  
  CONCLUSIONS
  Dosimetrically and clinically 3DCRT is better than conventional technique regarding parotid gland protection.
authors.affiliation: Department of Radiation Oncology, Tri-Service General Hospital, Taiwan, ROC. yeeminjen@yahoo.com.tw
authors.forename: Yee-Min
authors.initials: YM
authors.lastname: Jen
authors.forename: Rompin
authors.initials: R
authors.lastname: Shih
authors.forename: Yaoh-Shiang
authors.initials: YS
authors.lastname: Lin
authors.forename: Wan-Fu
authors.initials: WF
authors.lastname: Su
authors.forename: Chih-Hung
authors.initials: CH
authors.lastname: Ku
authors.forename: Chiou-Shiung
authors.initials: CS
authors.lastname: Chang
authors.forename: Pei-Wei
authors.initials: PW
authors.lastname: Shueng
authors.forename: Jing-Min
authors.initials: JM
authors.lastname: Hwang
authors.forename: Dai-Wei
authors.initials: DW
authors.lastname: Liu
authors.forename: Hsing-Lung
authors.initials: HL
authors.lastname: Chao
authors.forename: Hon-Yi
authors.initials: HY
authors.lastname: Lin
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Chang
authors.forename: Weng-Yoon
authors.initials: WY
authors.lastname: Shum
authors.forename: Chun-Shu
authors.initials: CS
authors.lastname: Lin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D010306:Parotid Gland / Q000528:radiation effects*; D011832:Radiation Injuries / Q000517:prevention & control*; D020266:Radiotherapy, Conformal / Q000379:methods*; D014987:Xerostomia / Q000209:etiology* / Q000517:prevention & control*