title: Dosimetric advantages of intensity-modulated proton therapy for oropharyngeal cancer compared with intensity-modulated radiation: A case-matched control analysis.
abstract: A potential advantage of intensity-modulated proton therapy (IMPT) over intensity-modulated (photon) radiation therapy (IMRT) in the treatment of oropharyngeal carcinoma (OPC) is lower radiation dose to several critical structures involved in the development of nausea and vomiting, mucositis, and dysphagia. The purpose of this study was to quantify doses to critical structures for patients with OPC treated with IMPT and compare those with doses on IMRT plans generated for the same patients and with a matched cohort of patients actually treated with IMRT. In this study, 25 patients newly diagnosed with OPC were treated with IMPT between 2011 and 2012. Comparison IMRT plans were generated for these patients and for additional IMRT-treated controls extracted from a database of patients with OPC treated between 2000 and 2009. Cases were matched based on the following criteria, in order: unilateral vs bilateral therapy, tonsil vs base of tongue primary, T-category, N-category, concurrent chemotherapy, induction chemotherapy, smoking status, sex, and age. Results showed that the mean doses to the anterior and posterior oral cavity, hard palate, larynx, mandible, and esophagus were significantly lower with IMPT than with IMRT comparison plans generated for the same cohort, as were doses to several central nervous system structures involved in the nausea and vomiting response. Similar differences were found when comparing dose to organs at risks (OARs) between the IMPT cohort and the case-matched IMRT cohort. In conclusion, these findings suggest that patients with OPC treated with IMPT may experience fewer and less severe side effects during therapy. This may be the result of decreased beam path toxicities with IMPT due to lower doses to several dysphagia, odynophagia, and nausea and vomiting-associated OARs. Further study is needed to evaluate differences in long-term disease control and chronic toxicity between patients with OPC treated with IMPT in comparison to those treated with IMRT.
authors.affiliation: Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Emma B
authors.initials: EB
authors.lastname: Holliday
authors.affiliation: Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX; Department of Radiation Therapy, Beykent University, Istanbul, Turkey.
authors.forename: Esengul
authors.initials: E
authors.lastname: Kocak-Uzel
authors.affiliation: Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Lei
authors.initials: L
authors.lastname: Feng
authors.affiliation: Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Nikhil G
authors.initials: NG
authors.lastname: Thaker
authors.affiliation: Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Pierre
authors.initials: P
authors.lastname: Blanchard
authors.affiliation: Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: David I
authors.initials: DI
authors.lastname: Rosenthal
authors.affiliation: Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: G Brandon
authors.initials: GB
authors.lastname: Gunn
authors.affiliation: Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Adam S
authors.initials: AS
authors.lastname: Garden
authors.affiliation: Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX. Electronic address: sjfrank@mdanderson.org.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Frank
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058958:Organs at Risk; D009959:Oropharyngeal Neoplasms / Q000532:radiotherapy*; D061766:Proton Therapy / Q000009:adverse effects / Q000379:methods*; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*
keywords: Acute toxicity; Dosimetric analysis; IMPT; Oropharyngeal carcinoma; Proton radiotherapy