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

Menée à partir des données d'un essai portant sur 482 patients atteints d'un cancer du poumon non à petites cellules de stade localement avancé et ayant reçu un traitement comportant une radiothérapie et une chimiothérapie concomitante par carboplatine-paclitaxel en combinaison ou non avec le cétuximab (durée médiane de suivi : 21,3 mois), cette étude compare l'efficacité, du point de vue de la survie globale à 2 ans, et la toxicité d'une radiothérapie avec modulation d'intensité et d'une radiothérapie externe conformationnelle 3D

Journal of Clinical Oncology, sous presse, 2016, résumé

Résumé en anglais

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 486 mL; 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-year OS, progression-free survival, local failure, and distant metastasis–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 on multivariable 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.