Prognostic implication of pulmonary function at the beginning of postoperative radiotherapy in non-small cell lung cancer

Purpose: The purpose of this study was to investigate the prognostic effect of pulmonary function at the beginning of postoperative radiotherapy (PORT) in non-small cell lung cancer (NSCLC). Materials and methods: From January 2002 to December 2012, 115 patients with NSCLC who underwent PORT and took the forced expiratory volume in 1 second (FEV1) at the beginning of PORT were analysed. PORT began within 4–6 weeks following surgery, and the 3-dimensional conformal technique was used with conventional fractionation. The high and low FEV1 groups were divided by the median absolute value of FEV1 at the beginning of PORT, and we compared the clinical factors and survival between two groups. Results: The median absolute value of FEV1 at the beginning of PORT was 1.68 L (range, 0.83–3.89), and patients were divided into low and high FEV1 groups (<1.68 L versus ⩾1.68 L). Patients in the low FEV1 group showed a lower preoperative FEV1 (mean, 1.94 L versus 2.73 L, p < 0.001) and received more pneumonectomy (36.8% versus 8.6%, p < 0.001) compared to the high FEV1 group. The overall median follow-up time was 31 months (range, 3–110), and 5-year locoregional recurrence-free survival (LRRFS), distant metastasis-free survival (DMFS) and overall survival (OS) were 52.4%, 48.9%, and 45.9%, respectively. Five-year OS of the low FEV1 group was significantly lower than that of the high FEV1 group (35.4% versus 56.9%, p = 0.002), and no significant differences were found in LRRFS and DMFS. In a multivariate analysis, the difference of OS between the low and high FEV1 groups remained significant (Hazard Ratio = 2.04, CI, 1.18–3.55, p = 0.011). Conclusions: The FEV1 at the beginning of PORT was an independent significant prognostic factor in patients with NSCLC who received PORT. Considering this analysis was limited to only patients receiving PORT, further studies are warranted to compare the survival effect of postoperative pulmonary function between groups with/without PORT