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

The objective of this study was to report on US radiation oncologists' (ROs) practice patterns and perceptions of concurrent radiation (RT) and immunotherapy (IT) (CRI).

A 22-question survey was emailed to radiation oncologists in February 2018. CRI was defined as RT completed within 1 week before initial IT infusion through 4 weeks after final IT infusion.

Of the 323 respondents from 45 states, 88% had experience treating a patient with CRI, including 51% private and 48% academic physicians. The most common reason for not offering CRI was concerns of increased toxicity (50%). Although 84% to 94% of respondents did not change RT dose, more ROs decreased dose when treating central structures (chest/abdomen/pelvis) versus noncentral structures (brain/head and neck/extremities): 13% to 15% versus 4% to 8%, P<0.001. The majority (58% to 80%) of respondents would not delay RT from last IT infusion. Moderate and significant actual toxicities were rare (medical intervention 6%, hospitalization/death <1%). 97.5% of ROs did not routinely prescribed prophylactic steroids for CRI. More ROs believed CRI with SBRT/SRS versus palliative RT had better local control (35% vs. 25%, P<0.05) and higher rates of abscopal responses (41% vs. 25%, P<0.01).

Despite concerns for toxicity, ROs with CRI experience reported minimal toxicities. Most ROs do 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, with a perception that concurrent SBRT offers better outcomes than palliative RT. These survey results may help guide ROs until more definitive data are available.