Amiodarone Use and Radiation Pneumonitis in Patients Undergoing Stereotactic Body Radiation Therapy for Non-Small Cell Lung Cancer

Abstract

Stereotactic body radiation therapy (SBRT) has become a standard of care for inoperable early-stage non-small cell lung cancer (NSCLC) patients. Amiodarone is a well-known cause of pneumonitis and an increasing number of patients treated with SBRT are also on amiodarone. Given this potential risk of pulmonary toxicity, it is of interest to examine whether amiodarone may potentiate the risk of RP. We sought to examine the impact of amiodarone use on RP in patients treated with SBRT. Patients with early-stage NSCLC who were taking amiodarone and underwent SBRT from January 2005 to January 2019 were identified from an IRB-approved institutional database. Amiodarone was required to be taken within 3 months before or after SBRT for inclusion. RP status was confirmed using CTCAE guidelines. Follow-up was defined as the time from the end of SBRT treatment until the most recent follow-up or date of death. Thirty-three patients met the inclusion criteria. Median follow up was 14 months (range, 1 to 55 months). The median dose of radiation was 54 Gy (range, 45 to 60) delivered in 3 to 12 fractions. Three patients (9%) developed radiation pneumonitis; all cases of pneumonitis were grade 2. One patient (3%) had a diagnosis of interstitial lung disease (ILD) and no presence of pneumonitis. In this single-institution series, the use of amiodarone in concert with lung SBRT was not associated with numerically increased rates of RP compared with the established literature. These results will need to be validated in larger cohorts with proper control of established metrics (lung V20, ILD), as well as other patient populations such as those undergoing cardiac radio-ablation, where the risks and mechanisms of injury may be different.