Postoperative Radiation Therapy (PORT) Is Safe and Effective in pIII-N2 Non-Small-Cell Lung Cancer (NSCLC) Receiving Pneumonectomy

Abstract

For patients with pIII-N2 NSCLC who received pneumonectomy followed by adjuvant chemotherapy, there are few evidence on the use of PORT and its role remains controversial. This study is to evaluate the safety and efficacy of PORT for such population. Between Jan. 2004 and Dec. 2015, patients with stage pIII-N2 NSCLC who had undergone pneumonectomy followed by adjuvant chemotherapy with or without PORT in our institution were retrospectively reviewed. Platinum-based doublet chemotherapy of 4 cycles was used. Radiotherapy was performed by 3D-CRT/ IMRT to the total dose of 50-60 Gy. The effect of PORT on survival was evaluated by Kaplan-Meier method and log-rank test. Pearson chi-Square test was used to compare categorical variables between groups. Student-t test was used for normal distribution variables, and Mann-Whitney U test was used for non-normal distribution variables. Statistically significant difference was set as p<0.05. Totally 119 patients with stage pIII-N2 NSCLC were included in this study. Among them, 32 patients received sequential adjuvant chemotherapy and PORT (PORT group), and 87 patients received adjuvant chemotherapy alone (Control group). Clinical and pathological characteristics of patients between the two groups were comparable (p>0.05), which included age, gender, KPS, tumor site, preoperative lung function and pathological type, et al. R1/R2 resection of PORT group was significantly higher than that of Control group (25% vs. 8%, p=0.031). Grade 2 or above radiation induced acute or chronic pneumonitis was 2/ 32. No severe radiation induced heart injury was observed. There was no radiation toxicity related death. Of all the 119 patients, the median follow-up time was 25 months and median overall survival (mOS) was 46months. The median disease free survival (mDFS) was 15 months. OS in PORT group was significantly better than control group (not reached vs. 34 months, p=0.003), and so as to DFS (19 months vs. 13 months, p=0.003). PORT could also significantly increase local recurrence free survival (LRFS, p=0.012) and distant metastasis free survival (DMFS, p=0.047). In patients with R0 resection (n=104), OS and LRFS in PORT group were significantly higher than those in Control group, and postoperative radiotherapy tended to increase DFS and DMFS with curves not crossing. For paitients with R1/R2 resection (n=15), OS in PORT group was also significantly higher than that in Control group (not reach vs. 24 months, p=0.021). Compared with chemotherapy alone, adding radiotherapy significantly reduced local regional failure rate (39.1% vs. 15.6%, p=0.016), and distant metastasis was still the main cause of failure. For patients with stage pIII-N2 NSCLC after pneumonectomy followed by adjuvant chemotherapy, PORT was safe and could improve OS, DFS, LRFS and DMFS. Further verification of our result is needed in the future study.