Reports have suggested improvements in dosimetry, toxicity, and quality of life with intensity-modulated radiation therapy (IMRT) in locally advanced non-small-cell lung cancer (NSCLC). The selection criteria for those patients who may benefit is unclear. This study sought to identify subgroups of patients who may derive survival benefit from intensity modulated radiation therapy (IMRT) compared with 3D conformal radiation therapy (3DCRT).

The National Cancer Data Base was queried for stage III NSCLC treated with radiation and chemotherapy alone with curative intent. All received ≥ 58 Gy. Kaplan-Meier and log-rank test were performed to compare overall survival (OS) by treatment modality. A multivariable Cox proportional hazards model was used to assess association with OS. Propensity score matching was also implemented.

A total of 2543 patients treated between 2003 and 2006 were eligible; 422 (16.6%) received IMRT, 2121 (83.4%) received 3DCRT. In patients with T3 and T4 disease, IMRT was associated with an improvement in median OS and 5-year survival rate (17.2 vs. 14.6 months; 19.9% vs. 13.4%, P = .021.) In multivariable analysis, there was an interaction between treatment type and T stage that was found to be significant (P = .03). In the propensity matched cohort of T3 and T4 patients, the use of IMRT remained associated with improved OS (hazard ratio, 0.80; 95% confidence interval, 0.64-1.00; P = .048).

Use of IMRT in patients with T3 and T4 tumors was associated with improved overall survival in this large population-based analysis. This is a novel finding that is in concordance with the well-described dosimetric benefits of IMRT in NSCLC.