Intensity-modulated radiation therapy versus volumetric-modulated arc therapy in non-small cell lung cancer: assessing the risk of radiation pneumonitis

Purpose: This study aimed to compare intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) regarding plan quality and healthy lung sparing, in stage III non-small cell lung cancer (NSCLC) patients. Materials and methods: The plans of 60 patients were allocated either to the IMRT (n=30) or the VMAT (n=30) group. The dose prescribed to the planning target volume (PTV) was evaluated at the 95% level and the mean lung dose (MLD) and the healthy lung receiving 5, 10 and 20 Gy (V-5, V-10 and V-20, respectively) were analysed. The normal tissue complication probability (NTCP) for radiation pneumonitis was calculated with the Lyman-Kutcher-Burman model. Results: Both techniques achieved comparable results for target coverage (V-95%=97.87 versus 97.18%, p>0.05) and homogeneity. The MLD (15.57 versus 16.98 Gy, p>0.05), V-5 (60.35 versus 67.25%, p>0.05) and V-10 (45.22 versus 53.14%, p=0.011) were lower for IMRT, whereas VMAT reduced V-20 (26.44 versus 25.90%, p>0.05). The NTCP for radiation pneumonitis was higher for VMAT, but no statistical significance was observed (11.07 versus 12.75, p>0.05). Conclusion: Both techniques seemed suitable for NSCLC treatment, but IMRT presented better results regarding lung sparing thus being beneficial in reducing the risk of radiation-induced pneumonitis.