Background: The optimal radiation dose for stage III non-small cell lung cancer (NSCLC) remains unclear. This study aimed to investigate the radiation dose-response relationship in patients with stage III NSCLC treated with definitive radiation therapy.


Methods: This retrospective cohort study analyzed 376 patients with stage III NSCLC treated with definitive radiation therapy between 2010 and 2019. The study population had a median age of 68 years, with 64.9% being male and 89.4% having a performance status of ECOG 0-1. The median radiation dose was 66 Gy, with 74.5% of patients receiving conventional fractionation and 25.5% receiving hypofractionated radiation.


Results: The median overall survival (OS) was 24.5 months, with a 95% confidence interval (CI) of 13.1-32.9 months. For every 1 Gy increase in radiation dose, the hazard of death decreases by 6% (HR = 0.94, p < 0.001). Older age is associated with a higher hazard of death (HR = 1.02, p = 0.002). Poorer performance status (ECOG 2-3) is associated with a higher hazard of death compared to good performance status (ECOG 0-1) (HR = 1.63, p = 0.009). Histology other than adenocarcinoma is associated with a higher hazard of death (HR = 1.55, p = 0.02). The results of the PCA suggest that the 15 dosimetric variables can be reduced to 5 components that explain 88.4% of the variance in the data suggesting that higher doses to smaller tumor volumes may be associated with better treatment outcomes.


Conclusion: Higher radiation doses may be associated with improved OS, but in patients with smaller tumor size. Further studies are needed to confirm these findings and to determine the optimal radiation dose for this patient population.