Radiation pneumonitis following concurrent accelerated hyperfractionated radiotherapy and chemotherapy for limited-stage small-cell lung cancer: Dose-volume histogram analysis and comparison with conventional chemoradiation.

PURPOSE The aim of this study was twofold: to determine whether the dose-volume metrics are valuable in predicting radiation pneumonitis (RP) in small-cell lung cancer (SCLC) patients treated with accelerated hyperfractionated radiotherapy and chemotherapy (AHFRT + CT); and to clarify how AHFRT influences the risk of RP in comparison to conventional once-daily radiotherapy and chemotherapy (QDRT + CT). METHODS AND MATERIALS Study subjects were 43 patients with SCLC treated with AHFRT + CT. Radiotherapy was delivered at 1.5 Gy/fraction (fr) twice daily to 45 Gy/30 fr/3 weeks. We analyzed the relation between RP incidence and several dosimetric factors. We also compared this series data with our previously published data from lung cancer patients treated with QDRT + CT. RESULTS Radiation pneumonitis Grades 1, 2, and 3 were observed in 28 patients, 7 patients, and 1 patient, respectively. Univariate analysis revealed that the percentage of lung volume receiving more than 15 Gy, 20 Gy, and 30 Gy (V15, V20, V30) and normal tissue complication probability were of predictive value for the development of RP. The 12-month cumulative incidences of RP greater than Grade 2 were 0%, 7.1%, 25%, and 42.9% in patients with a V20 of < or =20%, 21-25%, 26-30%, and > or =31%, respectively. These incidences were lower than that of our patients treated with QDRT + CT. CONCLUSIONS Dosimetric factors are valuable in predicting RP in SCLC patients treated with AHFRT + CT. Regarding the incidence of RP, AHFRT appears to have some advantage over QDRT.