Intensity-modulated proton therapy and osteoradionecrosis in oropharyngeal cancer

Publication date: Available online 23 May 2017
Source:Radiotherapy and Oncology
Author(s): Wencheng Zhang, Xiaodong Zhang, Pei Yang, Pierre Blanchard, Adam S. Garden, Brandon Gunn, C. David Fuller, Mark Chambers, Katherine A. Hutcheson, Rong Ye, Stephen Y. Lai, Mohamed Abdallah Sherif Radwan, X. Ron Zhu, Steven J. Frank
PurposeWe compared mandibular doses and osteoradionecrosis in patients with oropharyngeal cancer after intensity-modulated radiation therapy (IMRT) or intensity-modulated proton therapy (IMPT).Methods and materialsWe identified 584 patients who received definitive radiotherapy for oropharyngeal cancer from January 2011 through June 2014 at MD Anderson Cancer Center (534 IMRT and 50 IMPT). The dosimetric variables and osteoradionecrosis were compared with Chi-square test or Fisher's exact test.ResultsMedian follow-up time for all patients (534 IMRT and IMPT) was 33.8months (33.8months IMRT vs. 34.6months IMPT, P=0.854), and median time to osteoradionecrosis was 11.4months (range 6.74–16.1months). Mandibular doses were lower for patients treated with IMPT (minimum 0.8 vs. 7.3Gy; mean 25.6 vs. 41.2Gy; P<0.001), and osteoradionecrosis rates were lower as well: 2% IMPT (1 grade 1), 7.7% IMRT (12 grade 4, 5 grade 3, 1 grade 2 and 23 grade 1). Osteoradionecrosis location depended on the primary tumor site and high-dose field in the mandible.ConclusionsOsteoradionecrosis events were significantly associated with higher dose irradiation to mandibular. Use of IMPT minimized excess irradiation of the mandible and consequently reduced the risk of osteoradionecrosis for oropharyngeal cancer.



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