The Association Between Radiation to the Immune System and Overall Survival and Disease Progression in Non-Small Cell Lung Cancer Treated With Stereotactic Body Radiation Therapy

148 patients were included. 55% are female with a median age of 73 years. 23% had central lesions. 97% had diagnostic PET scan and all were treated with a mean dose of 50 Gy and Biological Effective Dose (BED) above 100 Gy. With a median follow up of 29 months, 34% of patients developed failure. The 2-year OS was 54%. In multivariate analysis, higher EDRIC (HR: 2.04) and lower KPS (HR: 0.35) continued to be associated with worse OS (P = 0.02 and P = 0.008). Considering each EDRIC quartile, there was a statistically significant difference in OS between 1st and 4 and 1 and 3 quartile (P = 0.01, P = 0.02). The median OS in each quartile is as followed: not reached, 47, 21, 21 months. There was no association between EDRIC and PFS. However, in multivariate analysis, KPS was associated with any type of failure (HR: 0.12, P = 0.013) CONCLUSION: This study showed that EDRIC can affect OS in patients with early staged NSCLC treated with SBRT. However, it does not affect PFS and any type of failure after receiving SBRT.