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TU_23_3540 - Concurrent Radiation and Immunotherapy: Survey of Practice Patterns in the United States

Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3

Concurrent Radiation and Immunotherapy: Survey of Practice Patterns in the United States
N. P. Amin1, C. Bergom2, N. Desai3, M. Agarwal4, J. Remick5, and C. B. Simone II1; 1Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, 2Medical College of Wisconsin, Milwaukee, WI, 3Medical College of Wisconsin, Department of Radiation Oncology, Milwaukee, WI, 4University of Maryland, Department of Radiation Oncology, Baltimore, MD, 5Department of Radiation Oncology, University of Maryland Medical Center, Baltimore, MD

Purpose/Objective(s): Rapid FDA approval of multiple immunotherapy (IT) drugs for a variety of advanced and metastatic cancers, coupled with a current void of published clinical data on toxicity and outcomes from concurrent radiation (RT) and immunotherapy (IT) (CRI), leave radiation oncologists (ROs) with uncertainty regarding their concurrent administration. A survey to determine current practice patterns, experiences, and perceptions of CRI may help guide ROs until more definitive data is available.

Materials/Methods: A survey was emailed to ROs over a 1-week period in February 2018. Responses were collected on Survey Monkey and descriptive statistics were used to report results. CRI was defined as RT completed within 1 week prior to initial IT infusion through 4 weeks after the final IT infusion.

Results: Of the 304 respondents from 44 states, 87.5% had experience treating a patient with CRI, including 50% private and 48% academic physicians. Results from the 266 ROs with prior CRI experience are summarized below. The majority of respondents have had limited experience with CRI: 60%, 56%, and 50% of respondents treated 1-5 patients on nivolumab, pembrolizumab, or ipilimumab, respectively, while 11-21%, 6-11%, and 4-8% have treated 5-10, 10-20 and >20 patients, respectively. 59% used CRI off-study, including 20% who prescribed a definitive RT course with concurrent IT. RT dose mostly was not altered: 13-15% decreased RT dose if treating the C/A/P, while 4-9% decreased dose in the brain, H/N, or extremities. For palliative RT vs SBRT/SRS to non-extremity sites, 65-67% vs 57-60% would not delay initiation of RT from IT infusion, while 12% vs 17-19% would wait ≥2 weeks from last IT infusion. For palliative RT vs SBRT to extremities, 80% vs 70% would not delay RT, but 5 vs 14% would wait 2 weeks. The two most common reasons for not offering CRI were due to concerns of increased toxicity (51%) or waiting to see response from newly initiated IT (40%). Moderate and significant toxicities were rare for all treatment sites and RT doses (medical intervention 6%, hospitalization/death <1%). 98% of ROs have not routinely prescribed prophylactic steroids for CRI. 49-59% of respondents remained uncertain if CRI vs RT monotherapy was improving local control or increasing abscopal responses, yet more ROs believed CRI with SBRT/SRS vs palliative RT had better local control (35% vs 25%) and higher rates of abscopal responses (40% vs 26%). Amongst the 38 ROs without prior CRI experience, 60% were concerned about increased toxicity, 32% would wait >2 weeks from IT to start SBRT/SRS, and 25% would offer prophylactic steroids.

Conclusion: Despite concerns for toxicity, ROs with CRI experience reported minimal toxicities regardless of treatment site or RT dose. Most ROs did not alter RT dose, use prophylactic steroids, or delay starting RT from last IT infusion. Uncertainty remains about improved local control outcomes and abscopal responses from CRI, yet there is a perception that concurrent SBRT offers better outcomes than palliative RT.

Author Disclosure: N.P. Amin: None. N. Desai: None. M. Agarwal: None. C.B. Simone: Employee; Nemours/Alfred I. duPont Hospital for Children. Chair, Executive Council; Chair, Lung Committee; Proton Collaborative Group (PCG). Editor-in-Chief; Annals of Palliative Medicine. Chair, Lung Resource Panel; American Society for Radiation Oncology.

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