Factors Associated with Short Interval from Treatment to Death in Patients Treated with Stereotactic Body Radiotherapy for Lung Metastases: Experience at a Large Academic Facility

Abstract

Stereotactic body radiotherapy (SBRT) is increasingly used to treat patients with lung metastases, as several studies have demonstrated a survival benefit in patients with oligometastatic disease, while in other cases it is used for palliation as in the re-irradiation setting. With increasing use, we queried whether SBRT is given more frequently toward the end of life for patients with lung metastases and assessed factors associated with a shorter interval from SBRT to death. A sample of patients who received stereotactic body radiation therapy (SBRT) to lung metastases between 2014-2022 at a single academic institution were identified. Medical records were reviewed for patient demographic, disease, and treatment details, including age, sex, race, insurance status, Karnofsky performance status (KPS), and time from SBRT to death. Descriptive statistics including chi-square and t-test analyses were used to compare patients who did versus did not die within 180 days of completion of SBRT. A total of 81 episodes of SBRT for lung metastases were identified. Of these, median age was 68 years (range 22-86), 82.7% had KPS >70, a majority had Medicare/Medicaid (61.7%, 50/81) or private insurance (33.3%, 27/81), and 63% were male. Only 9 of the 81 patients (11.1%) died within 180 days of SBRT completion. Death within 180 days occurred in 7.3% of treatments prior to 2018 compared to 15.0% of more recent treatments, but this difference was not statistically significant (p = 0.27; Table 1). Non-White race, KPS ≤70, and lack of insurance were all associated with increased likelihood of death within 180 days of SBRT (p<0.001 all comparisons). Few patients treated with SBRT for lung metastases in our series died within 180 days of SBRT completion, and there did not appear to be a significant increase in 180-day mortality post-SBRT in recent years. While limited by the small number of events, race, KPS, and insurance status were significantly associated with likelihood of death within 180 days of SBRT. Additional work is needed to better appreciate what patients may benefit from SBRT for lung metastases. Table 1: Characteristics of patients that did versus did not die within 180 days of SBRT for lung metastases.