Background: Role of tumor-stroma ratio (TSR) as a predictor of survival in patients with non-small cell lung cancer (NSCLC) remains not clear. A systematic review and meta-analysis was conducted to summarize current evidence for the role of TSR in NSCLC.Methods: Relevant cohort studies were retrieved via search of Medline, Embase, and Web of Science databases. The data was combined with a random-effect model by incorporating the between-study heterogeneity. Specifically, subgroup and meta-regression analyses were performed to explore the association between TSR and survival in patients with squamous cell carcinoma (SCC) or adenocarcinoma (AC).Results: Nine cohort studies with 2031 patients with NSCLC were eligible for the meta-analysis. Pooled results showed that compared to those stroma-poor tumor, patients with stroma rich NSCLC were associated with worse recurrence-free survival (RFS, hazard ratio [HR] = 1.52, 95% confidence interval [CI]: 1.07 to 2.16, p = 0.02) and overall survival (OS, HR = 1.48, 95% CI: 1.20 to 1.82, p < 0.001). Subgroup analyses showed that stroma-rich tumor may be associated with a worse survival of SCC (HR = 1.89 and 1.47 for PFS and OS), but a possibly favorable survival of AC (HR = 0.28 and 0.69 for PFS and OS). Results of meta-regression analysis also showed that higher proportion of patients with SCC was correlated with higher HRs for RFS (Coefficient = 0.012, p = 0.03) and OS (Coefficient = 0.014, p = 0.02) in the included patients, while higher proportion of patients with AC was correlated with lower HRs for RFS (Coefficient = −0.012, p = 0.03) and OS (Coefficient = −0.013, p = 0.04), respectively.Conclusion: Tumor TSR could be used as a predictor of survival in patients with NSCLC. The relative proportion of patients with SCC/AC in the included NSCLC patients may be an important determinant for the association between TSR and survival in NSCLC. Stroma richness may be a predictor of poor survival in patients with lung SCC, but a predictor of better survival in patients with lung AC.

Consensus remains lack regarding whether sleepdisordered breathing (SDB) is an independent risk factor for lung cancer. We therefore conducted a metaanalysis to clarify the relationship of SDB and lung cancer. Longitudinal follow-up studies investigating the association between SDB and incidence of lung cancer were included by search of electronic databases including PubMed, Embase, and Cochrane's Library. A randomeffects model was adopted to combine the results. Seven studies were included. Pooled results showed that presence of SDB was independently associated with higher incidence of lung cancer [adjusted risk ratio (RR): 1.28; 95% confidence interval (CI), 1.11-1.47; P < 0.001; I 2 = 37%]. Sensitivity analysis limited to studies with adjustment of smoking showed consistent results (three studies, RR: 1.34; 95% CI, 1.22-1.48; P < 0.001; I 2 = 8%). Subgroup analysis suggested that the association between SDB and higher risk of lung cancer was not significantly affected by study characteristics such as study design, source of population, sample size, evaluation methods for SDB, follow-up duration, methods for validation of lung cancer, or score of study quality (P values for subgroup difference all >0.05). No significant publication bias was observed (P for Egger's regression test = 0.258). These results suggested that SDB may be an independent risk factor of lung cancer in adult population. Intensive screening and prevention of lung cancer in subjects with SDB should be considered. European

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