1093 - A Double-Blinded Analysis of Radiation Dermatitis in Patients with Advanced Oropharyngeal Cancer Treated with IMPT vs. IMRT
Presenter(s)
K. E. Fink1, D. Swanson2, R. Ferrarotto2, E. M. Sturgis3, Z. Liao4, R. L. Foote5, P. M. Busse6, S. H. Patel7, J. W. Snider III8, G. B. Gunn9, M. W. McDonald10, N. S. Kalman11, S. R. Katz12, G. K. Bajaj13, C. Hyde14, C. Henson15, A. S. Garden9, D. J. Ma5, X. Zhang16, and S. J. Frank17; 1Feinberg School of Medicine, Chicago, IL, 2The University of Texas MD Anderson Cancer Center, Houston, TX, 3Baylor College of Medicine, Houston, TX, 4Department of Thoracic Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 5Department of Radiation Oncology, Mayo Clinic, Rochester, MN, 6Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 7Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, 8South Florida Proton Therapy Institute, Delary Beach, FL, 9Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, 10Winship Cancer Institute of Emory University, Atlanta, GA, 11Herbert Wertheim College of Medicine, Florida International University, Miami, FL, 12Willis-Knighton Cancer Center, Shreveport, LA, 13University of Maryland Medical Center, Baltimore, MD, 14Karmanos Cancer Institute at McLaren Flint, Flint, MI, 15University of Oklahoma Health Sciences Center, OKLAHOMA CITY, OK, 16Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, 17Department of Genitourinary Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
Purpose/Objective(s):
Radiation dermatitis is a common acute side effect of radiotherapy for oropharyngeal cancer (OPC). Intensity-modulated proton therapy (IMPT) is increasingly used for its ability to spare organs at risk relative to intensity-modulated photon radiation therapy (IMRT), but concerns remain about whether IMPT's higher entrance dose may worsen dermatitis. In this double-blinded study, we evaluated whether oncologists can discern, on photographic images of the head and neck, any difference in rates and severity of radiation dermatitis during or after IMPT vs IMRT for advanced OPC.Materials/Methods:
Eligible patients were enrolled in a national multicenter phase III randomized trial comparing concurrent chemoradiation therapy with IMPT vs IMRT for OPC. All patients were prescribed 70 Gy in 33 fractions to primary tumor. Standardized images of patients’ necks (front, back, left, right) were captured by professional medical photographers at baseline, mid-treatment, completion, and 8-12 weeks post-treatment (first follow-up). Patients with images from baseline, end of treatment, and at least one additional timepoint were included. Slides containing two baseline images and two on-treatment images side by side were generated for each patient. Slides were evaluated by a non-head and neck radiation oncologist, a head and neck surgical oncologist, and a head and neck medical oncologist, who graded radiation dermatitis as 0-4 per the Common Terminology Criteria for Adverse Events v4.0. Evaluators were blinded to both timepoint and treatment modality. Interobserver variability was assessed with Cohen’s kappa statistic, and proportions of grade 3+ dermatitis were compared across treatment modalities and neck N status with chi-square tests.Results:
We analyzed 298 slides (1,192 images) from 108 randomized patients (51 IMPT, 57 IMRT). Neck nodal status was not significantly different between IMPT and IMRT groups at any of the three time points (all p > 0.05). Interobserver agreement between the three evaluators was low at all three timepoints (?? = 0.15). No significant differences in rates or severity of radiation dermatitis were observed between IMRT and IMPT at mid-treatment, end of treatment, or first follow-up (all p > 0.05).Conclusion:
In this blinded study of patients undergoing IMPT vs IMRT for advanced OPC, rates and severity of high-grade radiation dermatitis were comparable between treatment groups. The dosimetric advantages of IMPT for sparing surrounding structures do not come at the expense of increased skin toxicity, reinforcing the potential safety and effectiveness of proton therapy for OPC.