Impact of Intensity-Modulated Radiation Therapy Technique for Locally Advanced Non-Small-Cell Lung Cancer: A Secondary Analysis of the NRG Oncology RTOG 0617 Randomized Clinical Trial

Purpose Although intensity-modulated radiation therapy (IMRT) is increasingly used to treat locally advanced non-small-cell lung cancer (NSCLC), IMRT and three-dimensional conformal external beam radiation therapy (3D-CRT) have not been compared prospectively. This study compares 3D-CRT and IMRT outcomes for locally advanced NSCLC in a large prospective clinical trial. Patients and Methods A secondary analysis was performed to compare IMRT with 3D-CRT in NRG Oncology clinical trial RTOG 0617, in which patients received concurrent chemotherapy of carboplatin and paclitaxel with or without cetuximab, and 60-versus 74-Gy radiation doses. Comparisons included 2-year overall survival (OS), progression-free survival, local failure, distant metastasis, and selected Common Terminology Criteria for Adverse Events (version 3) >= grade 3 toxicities. Results The median follow-up was 21.3 months. Of 482 patients, 53% were treated with 3D-CRT and 47% with IMRT. The IMRT group had larger planning treatment volumes (median, 427 v 486mL; P = .005); a larger planning treatment volume/ volume of lung ratio (median, 0.13 v 0.15; P = .013); and more stage IIIB disease (30.3% v 38.6%, P = .056). Two-yearOS, progression-free survival, local failure, and distantmetastasis-free survival were not different between IMRT and 3D-CRT. IMRT was associated with less >= grade 3 pneumonitis (7.9% v 3.5%, P = .039) and a reduced risk in adjusted analyses (odds ratio, 0.41; 95% CI, 0.171 to 0.986; P = .046). IMRT also produced lower heart doses (P < .05), and the volume of heart receiving 40 Gy (V40) was significantly associated with OS on adjusted analysis (P,.05). The lung V5 was not associated with any >= grade 3 toxicity, whereas the lung V20 was associated with increased >= grade 3 pneumonitis risk onmultivariable analysis (P = .026). Conclusion IMRT was associated with lower rates of severe pneumonitis and cardiac doses in NRG Oncology clinical trial RTOG 0617, which supports routine use of IMRT for locally advanced NSCLC. (C) 2016 by American Society of Clinical Oncology