Dose-Volume Parameters Predict Radiation Pneumonitis after Surgery with Induction Concurrent Chemoradiotherapy for Non-small Cell Lung Cancer

To clarify the relationship between dose-volume histogram (DVH) parameters and radiation pneumonitis (RP) after surgery in cases of non-small cell lung cancer (NSCLC) treated with induction concurrent chemoradiotherapy (CCRT). Patients with NSCLC treated with induction CCRT (chemotherapy: cisplatin and docetaxel; radiotherapy: 2.0 Gy fractions once daily for a total of 46 Gy) before surgery were reviewed. We calculated the percentage of lung volume receiving at least 20 Gy (V20) and the mean lung dose (MLD) for the total lung volume and the lung remaining after resection. Factors affecting the incidence of RP at grade 2 or higher (≥ G2 RP) were analyzed. Eighteen of 49 patients (37%) experienced ≥G2 RP. The V20 and MLD for the lung remaining after resection (V20r and MLDr) were significant predictors according to the multivariate analysis (p=0.007 and 0.041, respectively). The incidence of ≥G2 RP was 8% in patients with V20r<10%, and 13% in patients with MLDr<5.6 Gy, respectively. The optimal approach to reduce the rate of postoperative RP in patients with induction CCRT for NSCLC is to keep the V20r below 10% and/or the MLDr below 5.6 Gy in the radiotherapy planning.