Clinical and structural factors associated with access to stereotactic body radiation therapy (SBRT) in lung cancer.

Abstract

e20104 Background: Stereotactic body radiation therapy (SBRT) is an established treatment modality for select patients with non-small cell lung cancer (NSCLC). However, access to SBRT may be influenced not only by clinical disease characteristics but also by structural factors such as insurance coverage. Disentangling age-related eligibility from insurance-mediated access is essential to identifying inequities in treatment allocation and outcomes. Methods: We conducted a retrospective cohort study of 211 patients with lung cancer, stratified by receipt of SBRT to the primary lung lesion. Baseline demographic, clinical, tumor, and treatment characteristics were compared using chi-square or Fisher’s exact tests and Student’s t -tests or Wilcoxon rank-sum tests, as appropriate. Variables significant in bivariate analyses were visualized and entered into a multivariable logistic regression models to identify independent predictors of SBRT receipt, adjusting for age, race, sex, and smoking status. Overall survival (OS) was analyzed using Kaplan–Meier methods with log-rank testing, and multivariable Cox proportional hazards models evaluated the association between SBRT and OS. Survival time was defined from diagnosis to death, with censoring at last follow-up. Statistical significance was defined as p < 0.05. Results: Among 211 patients, 84 (39.8%) received SBRT. Mean age at diagnosis was similar between patients who received SBRT and those who did not (62.9 vs 61.9 years, p = 0.443), suggesting that age alone did not account for treatment differences. Patients receiving SBRT had significantly greater disease burden, including higher rates of stage IV disease (54.8% vs 29.9%, p = 0.003), metastatic disease (82.1% vs 48.0%, p < 0.001), chemotherapy use (94.0% vs 79.5%, p = 0.007), and immunotherapy use (51.2% vs 73.2%, p = 0.002). Body mass index category also differed significantly (p = 0.003), with SBRT recipients more frequently underweight, consistent with increased physiologic vulnerability. Despite comparable age, patients receiving SBRT were significantly less likely to have Medicare insurance (38.1% vs 55.1%, p = 0.023). At last follow up, fewer patients in the SBRT group were alive compared with those who did not receive SBRT (52.4% vs 70.1%, p = 0.014) likely reflecting higher baseline disease staging rather than treatment effect alone. Conclusions: In this cohort, receipt of SBRT was associated with higher disease burden and greater physiologic vulnerability, independent of age. Differences in payer status between treatment groups suggest that. insurance-related factors may influence referral patterns or access to advanced radiation modalities. These findings highlight the need to evaluate how payer status and treatment selection interact to affect survival and equity in lung cancer care.