Immunotherapy with and without radiotherapy following the diagnosis of bone metastasis for stage IV non-small cell carcinoma

INTRODUCTION: This retrospective study compared the impact of radiotherapy (RT) and immunotherapy (IO) on survival in patients with stage IV non-small cell lung cancer (NSCLC) following a diagnosis of bone metastasis. METHODS: The TriNetX database (2013-2024) was queried for adults (≥ 18 years) with NSCLC who received IO after diagnosis of bone metastases. Patients were then divided into cohorts based on whether they also received RT after bone metastasis diagnosis. RESULTS: A risk assessment revealed RT + IO was associated with significantly improved survival at 3 months (92% vs. 86% alive, p < 0.001), 6 months (79% vs. 72%, p = 0.002), and 1 year (59% vs. 54%, p = 0.014). In patients with adenocarcinoma, RT + IO was associated with improved survival at 3 months (92% vs. 88%, p = 0.046) but not at 6 months or 1 year. Similarly, in patients with squamous cell carcinoma, IO + RT was also associated with higher survival (94% vs. 85%, p = 0.040) at 3 months but not at 6 months or 1 year. A Cox proportional hazards model found significant lower hazard of death in the RT + IO group (hazard ratio [HR] = 0.83) and several covariates were associated with higher hazard, including adrenal metastasis (HR = 1.7), liver metastasis (HR = 1.4), lymph node metastasis (HR = 1.3), hypoalbuminemia (< 3.45 g/dL; HR = 1.5), and inpatient or observation care (HR = 1.4). DISCUSSION: This study highlights the potential importance of combining RT with IO, particularly in the early period after bone metastasis diagnosis.