title: Proton beam radiation therapy results in significantly reduced toxicity compared with intensity-modulated radiation therapy for head and neck tumors that require ipsilateral radiation.
abstract: BACKGROUND
  As proton beam radiation therapy (PBRT) may allow greater normal tissue sparing when compared with intensity-modulated radiation therapy (IMRT), we compared the dosimetry and treatment-related toxicities between patients treated to the ipsilateral head and neck with either PBRT or IMRT.
  
  
  METHODS
  Between 01/2011 and 03/2014, 41 consecutive patients underwent ipsilateral irradiation for major salivary gland cancer or cutaneous squamous cell carcinoma. The availability of PBRT, during this period, resulted in an immediate shift in practice from IMRT to PBRT, without any change in target delineation. Acute toxicities were assessed using the National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0.
  
  
  RESULTS
  Twenty-three (56.1%) patients were treated with IMRT and 18 (43.9%) with PBRT. The groups were balanced in terms of baseline, treatment, and target volume characteristics. IMRT plans had a greater median maximum brainstem (29.7 Gy vs. 0.62 Gy (RBE), ​P < 0.001), maximum spinal cord (36.3 Gy vs. 1.88 Gy (RBE), ​P < 0.001), mean oral cavity (20.6 Gy vs. 0.94 Gy (RBE), ​P < 0.001), mean contralateral parotid (1.4 Gy vs. 0.0 Gy (RBE), P<0.001), and mean contralateral submandibular (4.1 Gy vs. 0.0 Gy (RBE), ​P < 0.001) dose when compared to PBRT plans. PBRT had significantly lower rates of grade 2 or greater acute dysgeusia (5.6% vs. 65.2%, P<0.001), mucositis (16.7% vs. 52.2%, P=0.019), and nausea (11.1% vs. 56.5%, P=0.003).
  
  
  CONCLUSIONS
  The unique properties of PBRT allow greater normal tissue sparing without sacrificing target coverage when irradiating the ipsilateral head and neck. This dosimetric advantage seemingly translates into lower rates of acute treatment-related toxicity.
authors: Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, United States.
authors: Paul B
authors: PB
authors: Romesser
authors: Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, United States; ProCure Proton Therapy Center, Somerset, United States.
authors: Oren
authors: O
authors: Cahlon
authors: Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, United States; Rowan University School of Osteopathic Medicine, Stratford, United States.
authors: Eli
authors: E
authors: Scher
authors: Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, United States.
authors: Ying
authors: Y
authors: Zhou
authors: Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, United States.
authors: Sean L
authors: SL
authors: Berry
authors: Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, United States.
authors: Alisa
authors: A
authors: Rybkin
authors: ProCure Proton Therapy Center, Somerset, United States.
authors: Kevin M
authors: KM
authors: Sine
authors: ProCure Proton Therapy Center, Somerset, United States.
authors: Shikui
authors: S
authors: Tang
authors: Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, United States.
authors: Eric J
authors: EJ
authors: Sherman
authors: Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, United States.
authors: Richard
authors: R
authors: Wong
authors: Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, United States. Electronic address: leen2@mskcc.org.
authors: Nancy Y
authors: NY
authors: Lee
mesh_terms: D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy*; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D061766:Proton Therapy / Q000009:adverse effects / Q000379:methods*; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*; D012468:Salivary Gland Neoplasms / Q000532:radiotherapy*; D016896:Treatment Outcome
keywords: Head and neck cancer; IMRT; Proton beam; Proton beam radiation