Comparison between the first-line and second-line immunotherapy drugs in the progression-free survival and overall survival in advanced non-small cell lung cancer: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND Non-small cell lung cancer (NSCLC) accounts for the majority of lung cancer but with a low early diagnosis rate. With immunotherapy becomes popular in lung cancer, single immunotherapy drug treatment as the first-line or second-line plays an important role. The meta-analysis compares different clinical effects of them by overall survival (OS) and progression-free survival (PFS) because it is important to detect the best time of immunotherapy for NSCLC patients. METHODS Randomized controlled trials (RCTs) were selected by using the Cochrane Library, Embase, PubMed and Web of science. Pool the hazard ratio (HR) and use the PFS, OS as outcomes. RESULTS Ten RCTs were included. The pooled results indicated that first-line and second-line single immunotherapy drug treatment seems to have a tiny difference in PFS, with HR 0.79, 95% confidence interval (CI): 0.51-1.21, I2 =89% in first-line single immunotherapy drug treatment and HR 0.74, 95% CI: 0.62-0.89, I2 =84% in second-line single immunotherapy drug treatment. When it comes to OS, first-line immunotherapy drug treatment still has better effects than the second-line. In first-line single immunotherapy drug treatment, HR 0.78, 95% CI: 0.55-1.11, I2 =83%, but in second-line, HR 0.70, 95% CI: 0.64-0.76, I2 =53%. CONCLUSIONS First-line single drug immunotherapy had the tendency better than single immunotherapy drugs used in second-line treatment.