Identification of Clinical Predictors of Benefit of Palliative Thoracic Radiotherapy

Abstract

Palliative thoracic radiotherapy (PTRT) is frequently utilized for relief of pain, obstruction and hemoptysis from lung and bronchial primary tumors and metastatic disease. Historically, the prognosis for these patients has been dismal with radiotherapy (RT) often serving as a last line of therapy. However, with continued advancements in systemic therapies for non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC) and other malignancies, PTRT may provide increased benefit both in relief of symptoms and prolongation of life for select patients. In this study, we sought to determine clinical predictors of benefit of PTRT in a contemporary cohort of patients with the goal of aiding in appropriate patient selection for escalation or de-escalation of RT in patients with locally advanced or metastatic disease.Patients treated with standard palliative courses of RT, including 8 Gy/1 fx, 20 Gy/5 fx, and 30 Gy/10 fx, to the thoracic cavity between 2014 and 2020 were identified. Clinical information was collected, including age, ECOG PS, histology, stage, presence of brain metastases, presence of lung collapse, lines of previous systemic therapy, neutrophil-lymphocyte ratio (NLR), mutational status, and survival outcomes. Kaplan-Meier analyses were used for survival and sensitivity analyses. Cox regression was performed for multivariate analysis.161 evaluable patients were identified who received PTRT for various indications including dyspnea, SVC syndrome, hemoptysis, pain and obstruction/lung collapse. A majority of patients (61%) had a diagnosis of NSCLC, although SCLC (10%) and other histologies (29%) were also included. 94% of patients were metastatic at the time of receipt of PTRT. Multivariate analysis identified female sex, multi-fraction regimens, better baseline ECOG performance status, presence of an actionable mutation, absence of brain mets, and non-lung histologies as positive predictors of survival following PTRT (P < 0.05). Other factors including age, number of lines of systemic therapy and NLR were not identified as independent predictors in this cohort in either multivariate or univariate analyses. Notably, 14 patients failed to complete prescribed therapy all of whom had ECOG PS of 2 or greater at start of RT.Patients with symptomatic lung disease derive differential benefit from PTRT with ECOG 0-1, absence of brain mets and presence of actionable mutations important clinical predictors of longer-term survival following treatment. Single fraction courses should be strongly considered for poor PS patients who may derive less significant survival benefit from PTRT and are at higher risk for early treatment discontinuation.