Meta-analysis of postoperative adjuvant chemotherapy without radiotherapy in early stage non-small cell lung cancer

BACKGROUND: Many clinical trials have confirmed that postoperative adjuvant therapy can prolong survival of non-small cell lung cancer. However, the efficiency of postoperative chemotherapy without radiotherapy is unclear, especially in early stage (stages I and II). We aimed to assess the effect of postoperative chemotherapy without radiotherapy in early stage patients. METHODS: Databases and manual searches were adopted to identify eligible randomized control trials. Hazard ratio (HR) was used to assess the advantage of disease-free survival (DFS) and overall survival (OS) by fixed or random-effects models. RESULTS: Fourteen trials with 3,923 patients were included based on inclusion criteria. Compared with surgery alone, postoperative chemotherapy significantly improved DFS and OS with HR of 0.71 (P=0.005) and 0.74 (P<0.00001), respectively. Subgroup analysis showed both cisplatin-based (HR: 0.75, P<0.0001) and single tegafur–uracil (UFT) chemotherapy (HR: 0.72, P=0.002) yielded significant survival benefits, but the latter did not improve DFS (HR: 1.04, P=0.81). Indirect treatment comparison showed cisplatin-based chemotherapy was superior to single UFT in DFS, but comparable in OS. The benefits of postoperative chemotherapy were maintained in patients in stage I (HR: 0.74, P<0.00001) and IB (HR: 0.74, P=0.0003), but not in stage IA, although the trend supported chemotherapy (HR: 0.76, P=0.43). CONCLUSION: This meta-analysis demonstrates that postoperative chemotherapy without radiotherapy improves survival of stage I–II, I, and IB non-small cell lung cancer patients, but not for IA. Meanwhile, efficacy of cisplatin-based chemotherapy is comparable to single UFT in OS, but better in DFS, which should be paid more attention in future clinical practice.