title: High-dose and extended-field intensity modulated radiation therapy for early-stage NK/T-cell lymphoma of Waldeyer's ring: dosimetric analysis and clinical outcome.
abstract: OBJECTIVE
  To assess the dosimetric benefit, treatment outcome, and toxicity of high-dose and extended-field intensity modulated radiation therapy (IMRT) in patients with early-stage NK/T-cell lymphoma of Waldeyer's ring (WR-NKTCL).
  
  
  METHODS
  Thirty patients with early-stage WR-NKTCL who received extended-field IMRT were retrospectively reviewed. The prescribed dose was 50 Gy to the primary involved regions and positive cervical lymph nodes (planning target volume requiring radical irradiation [PTV50]) and 40 Gy to the negative cervical nodes (PTV40). Dosimetric parameters for the target volume and critical normal structures were evaluated. Locoregional control (LRC), overall survival (OS), and progression-free survival (PFS) were calculated using the Kaplan-Meier method.
  
  
  RESULTS
  The median mean doses to the PTV50 and PTV40 were 53.2 Gy and 43.0 Gy, respectively. Only 1.4% of the PTV50 and 0.9% of the PTV40 received less than 95% of the prescribed dose, indicating excellent target coverage. The average mean doses to the left and right parotid glands were 27.7 and 28.4 Gy, respectively. The 2-year OS, PFS, and LRC rates were 71.2%, 57.4%, and 87.8%. Most acute toxicities were grade 1 to 2, except for grade ≥3 dysphagia and mucositis. The most common late toxicity was grade 1-2 xerostomia, and no patient developed any ≥grade 3 late toxicities. A correlation between the mean dose to the parotid glands and the degree of late xerostomia was observed.
  
  
  CONCLUSIONS
  IMRT achieves excellent target coverage and dose conformity, as well as favorable survival and locoregional control rates with acceptable toxicities in patients with WR-NKTCL.
authors.affiliation: Department of Radiation Oncology, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P. R. China.
authors.forename: Xi-Wen
authors.initials: XW
authors.lastname: Bi
authors.forename: Ye-Xiong
authors.initials: YX
authors.lastname: Li
authors.forename: Hui
authors.initials: H
authors.lastname: Fang
authors.forename: Jing
authors.initials: J
authors.lastname: Jin
authors.forename: Wei-Hu
authors.initials: WH
authors.lastname: Wang
authors.forename: Shu-Lian
authors.initials: SL
authors.lastname: Wang
authors.forename: Yue-Ping
authors.initials: YP
authors.lastname: Liu
authors.forename: Yong-Wen
authors.initials: YW
authors.lastname: Song
authors.forename: Hua
authors.initials: H
authors.lastname: Ren
authors.forename: Jian-Rong
authors.initials: JR
authors.lastname: Dai
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D015182:Lymphatic Irradiation / Q000009:adverse effects / Q000379:methods; D054391:Lymphoma, Extranodal NK-T-Cell / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy; D009333:Neck; D009361:Neoplasm Invasiveness; D009669:Nose Neoplasms / Q000473:pathology / Q000532:radiotherapy; D059351:Organ Sparing Treatments / Q000379:methods; D058958:Organs at Risk / Q000000981:diagnostic imaging / Q000528:radiation effects; D009959:Oropharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy; D010306:Parotid Gland / Q000000981:diagnostic imaging / Q000528:radiation effects; D010610:Pharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D011859:Radiography; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D012189:Retrospective Studies; D016896:Treatment Outcome; D014987:Xerostomia / Q000209:etiology / Q000517:prevention & control; D055815:Young Adult