The impact of previous extrapulmonary malignancies on survival of surgically treated primary lung cancer: a comprehensive systematic review and meta-analysis

Whether a history of previous extrapulmonary malignancies had an impact on the survival of surgically treated primary lung cancer patients remains unknown. To better answer this question, we, therefore, conducted the first meta-analysis to compare the survival of lung cancer patients after surgical resection with previous extrapulmonary malignancies and those without. We systematically searched PubMed, Embase, and the Cochrane Library to identify relevant studies up to April 1, 2022. Data for analysis were obtained directly from the text results or calculated from the Kaplan–Meier survival curve, which mainly included 5-year overall survival (OS) and recurrence-free survival (RFS). Pooled hazard ratios (HRs) and 95% confidence intervals (CIs) were analyzed by the fixed-effect model test or standard random-effect model test depending on the heterogeneity of the included studies. The Q-test and I²-test were used to assess heterogeneity. Sensitivity analysis was performed to examine the stability of the pooled results. We finally included 7 retrospective studies consisting of 19,723 surgically treated primary lung cancer patients with (7.7%) or without (92.3%) previous extrapulmonary malignancies. The final results showed that lung patients with previous extrapulmonary malignancies had an inferior OS (HR 1.18, 95% CI [1.07, 1.31], P = 0.001) than those without, but no significant difference in RFS (HR 1.15, 95% CI [0.89–1.47], P = 0.29) was observed between the two groups. Moreover, when only focusing on stage-I primary lung cancer patients with or without previous extrapulmonary malignancies, the results still held true (OS: HR 1.39, 95% CI [1.04, 1.85], P = 0.02; RFS: HR 1.10, 95% CI [0.82–1.49], P = 0.51, respectively). No significant heterogeneities or publication bias were observed among these studies. Our meta-analysis showed that surgically treated primary lung cancer patients with a previous extrapulmonary cancer history had a worse overall survival than those without. However, a history of previous extrapulmonary cancer was not associated with postsurgical lung cancer recurrence, and more large-scale prospective studies should be encouraged to update our conclusions.