LAUSR

e18325 Background: Radiation therapy (RT) effectively palliates pain and other symptoms due to cancer and is frequently offered to patients with metastatic disease. Standard palliative RT schedules range from one to ≥10 fractions; however, prognostic variables related to survival following palliative RT are not well studied. A better understanding of prognostic factors in this setting will assist in selecting appropriate palliative RT regimens for patients with short life expectancies. Methods: Prospectively maintained institutional databases tracking morbidity and mortality and outcomes of a departmental peer review process were used to identify patients who received palliative RT between April 2015 - December 2018. Cox proportional hazards model was used to identify factors correlated with overall survival (OS) and mortality within 30 days (30DM) after completing palliative RT, including age, sex, admission status (inpatient versus outpatient), Karnofsky Performance Status (KPS), treated site and primary site. Results: Of 421 patients, 389 received palliative RT; 30DM rate was 25.7% (n = 100). Median age was 61, median KPS was 70, and 196 patients (50.4%) were female. The most common primary sites were thorax (N = 121, 31.1%) and genitourinary tract (N = 60, 15.4%), while the most commonly treated sites were brain (N = 136, 35.0%) and bone (N = 71, 18.3%). KPS and treatment site were strong independent predictors of both OS and 30DM. Patients with KPS < 70 had an HR 2.61 (95% CI 1.54 – 4.43, p < 0.0001) for 30DM and an HR of 2.22 (95% CI 1.57 – 3.13, p < 0.0001) for death at any time after RT. Treatment site was also independently associated with OS and 30DM (p = 0.01 and p = 0.03, respectively). Median OS durations (95%CI) were: abdomen/pelvis not reached, bone 340 days (133.9-546.1), spine 207 days (28.0 – 386.0), head and neck 184 days (55.2 – 312.8), brain 104 days (34.3 – 173.7) and thorax 76 days (10.3 – 141.7). Age, sex, admission status and primary site were not correlated with OS or 30DM. Conclusions: RT can effectively palliate distressing symptoms related to primary or metastatic cancers. However, early mortality is common following palliative RT and is associated with poor performance status and treated site. Hypofractionated RT courses should be considered in patients with such risk factors to reduce the burden of prolonged therapy on patients and their families at the end of life.