Abstract
BACKGROUND: The association between the location of non-small cell lung cancer (NSCLC) and prognosis is a debated issue. Some studies have provided evidence of better prognosis of upper lobe tumors than lower to middle lobe tumors, while other studies have reported contrasting conclusions. The aim of this study was to further assess this association through a systematic review and meta-analysis. METHODS: Medline, Embase, and the Cochrane Central Register of Controlled Trials were searched up to 27 January 2017. Patients pathologically diagnosed with stage I-III NSCLC with three or five-year survival data were included. The main meta-analysis compared differences in survival rates according to the primary tumor location using the Mantel-Haenszel method with a random effect model. Sensitivity analysis was conducted according to lymph node metastasis, tumor node metastasis stage, staging method, and treatment modality. RESULTS: Ten clinical studies and 35 570 patients were recruited. Patients with tumors in the upper lobes had a higher rate of five-year survival compared to those with tumors in non-upper lobes (odds ratio [OR] 1.31, 95% confidence interval [CI] 1.15-1.49). Similarly, the three-year survival rate was high in patients with tumors in the upper lobes (OR 1.99, 95% CI 1.02-3.86) and low in those with lower lobe tumors (OR 0.31, 95% CI 0.12-0.77). CONCLUSIONS: Stage I-III NSCLC located in the upper lobes showed higher five-year survival rates compared to other tumor locations.