Clinicopathological and prognostic significance of thyroid transcription factor-1 expression in small cell lung cancer: A systemic review and meta-analysis

Purpose: To explore the association of thyroid transcription factor-1 (TTF-1) expression status with dinicopathological characteristics and survival of patients with small cell lung cancer (SCLC). Methods: A comprehensive literature search was conducted to identify potentially relevant studies in several electronic databases, including EMBASE, PubMed, Web of Science, CNKI and WanFang. The relative risks (RRs) and hazard ratios (HRs) with 95% confidence intervals (CIs) were used to assess the relation of TTF-1 with clinicopathological parameters and prognosis, respectively. Sensitivity analysis was performed to assess the stability of the pooled results. Begg's funnel plot and Egger's test were applied to detect the publication bias. All statistical analyses were performed by STATA 12.0 version software. Results: A total of 11 studies involving 1786 SCLC patients were included in our study. No significant relationship between TTF-1 and any clinicopathological features was observed. However, the pooled results demonstrated that TTF-1 expression indicated prolonged overall survival (OS) (HR = 0.56, 95% CI: 0.45-0.70; P < 0.001) and progression-free survival (PFS) (HR = 0.41, 95% CI: 0.28-0.62; P < 0.001). Subgroup analysis stratified by the country manifested that the significant prognostic value of ITF-1 expression status was only observed in SCLC patients who from China. Conclusion: TTF-1 might be an independent prognostic factor in SCLC patients, especially patients who were from China. More well-designed prospective studies are needed to further testify our findings.