title: A retrospective comparison of robotic stereotactic body radiotherapy and three-dimensional conformal radiotherapy for the reirradiation of locally recurrent nasopharyngeal carcinoma.
abstract: OBJECTIVE
  We assessed therapeutic outcomes of reirradiation with robotic stereotactic radiotherapy (SBRT) for locally recurrent nasopharyngeal carcinoma (LRNPC) patients and compared those results with three-dimensional conformal radiotherapy (CRT) with or without brachytherapy (BRT).
  
  
  METHODS
  Treatment outcomes were evaluated retrospectively in 51 LRNPC patients receiving either robotic SBRT (24 patients) or CRT with or without BRT (27 patients) in our department. CRT was delivered with a 6-MV linear accelerator, and a median total reirradiation dose of 57 Gy in 2 Gy/day was given. Robotic SBRT was delivered with CyberKnife (Accuray, Sunnyvale, CA). Patients in the SBRT arm received 30 Gy over 5 consecutive days. We calculated actuarial local control and cancer-specific survival rates for the comparison of treatment outcomes in SBRT and CRT arms. The Common Terminology Criteria for Adverse Events v3.0 was used for toxicity evaluation.
  
  
  RESULTS
  The median follow-up was 24 months for all patients. Two-year actuarial local control rates were 82% and 80% for SBRT and CRT arms, respectively (p = 0.6). Two-year cancer-specific survival rates were 64% and 47% for the SBRT and CRT arms, respectively (p = 0.4). Serious late toxicities (Grade 3 and above) were observed in 21% of patients in the SBRT arm, whereas 48% of patients had serious toxicity in the CRT arm (p = 0.04). Fatal complications occurred in three patients (12.5%) of the SBRT arm, and four patients (14.8%) of the CRT arm (p = 0.8). T stage at recurrence was the only independent predictor for local control and survival.
  
  
  CONCLUSIONS
  Our robotic SBRT protocol seems to be feasible and less toxic in terms of late effects compared with CRT arm for the reirradiation of LRNPC patients.
authors.affiliation: Hacettepe University, Faculty of Medicine, Department of Radiation Oncology, Ankara, Turkey. gozyigit@hacettepe.edu.tr
authors.forename: Gokhan
authors.initials: G
authors.lastname: Ozyigit
authors.forename: Mustafa
authors.initials: M
authors.lastname: Cengiz
authors.forename: Gozde
authors.initials: G
authors.lastname: Yazici
authors.forename: Ferah
authors.initials: F
authors.lastname: Yildiz
authors.forename: Murat
authors.initials: M
authors.lastname: Gurkaynak
authors.forename: Faruk
authors.initials: F
authors.lastname: Zorlu
authors.forename: Demet
authors.initials: D
authors.lastname: Yildiz
authors.forename: Sefik
authors.initials: S
authors.lastname: Hosal
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Gullu
authors.forename: Fadil
authors.initials: F
authors.lastname: Akyol
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002277:Carcinoma; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery*; D009364:Neoplasm Recurrence, Local / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery*; D016634:Radiosurgery / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D019233:Retreatment / Q000009:adverse effects / Q000379:methods; D012189:Retrospective Studies; D012371:Robotics / Q000379:methods*; D016879:Salvage Therapy / Q000009:adverse effects / Q000379:methods / Q000401:mortality; D015996:Survival Rate; D016896:Treatment Outcome; D055815:Young Adult