Abstract
ObjectiveIt has been confirmed that the micropapillary (MP) pattern is a poor prognostic factor after resection of lung adenocarcinoma (ADC), but the proportion of the MP component as a prognostic criterion is still controversial. Hence, a meta-analysis was performed to evaluate whether the presence of an MP component has equal prognostic power as the MP predominant subtype.MethodsLiterature retrieval was performed in the MEDLINE, EMBASE, and Cochrane databases until December 23, 2019. Eligible studies were selected based on the inclusion and exclusion criteria. The included studies were divided into two subgroups, the MP component subgroup and the MP predominant subgroup, according to the proportion of the MP pattern to analyse the effect of this pattern on disease-free survival (DFS) and overall survival (OS). The hazard ratio (HR) and 95% confidence interval (CI) were extracted from each study. Review Manager 5.3 was used for statistical analyses.ResultsFinally, 10 studies, including a total of 4934 lung ADC patients, were included in this meta-analysis. Our results indicated a significantly worse pooled DFS (HR 1.62, 95% CI 1.20–2.21) and OS (HR 1.53, 95% CI 1.19–1.96) in the subgroup of MP predominant subtype patients. The pooled DFS (HR 1.80, 95% CI 1.45–2.85) and OS (HR 2.26, 95% CI 1.46–3.52) were also poor in the subgroup of patients with the presence of an MP component.ConclusionsBoth the presence of an MP component and the MP predominant subtype are related to poor DFS and OS after lung ADC resection and represent adverse prognostic factor for lung ADC patients. However, there are some limitations in this meta-analysis, and quantitative stratification based on the proportion of the MP component is needed to explore its effect on prognosis of lung ADC patients in the future.
Highlights
Primary bronchial lung cancer is one of the most malignant tumours with the highest morbidity and mortality in China and the world, seriously endangering human health [1]
The selected studies met the following criteria: (1) the research subjects were patients with confirmed lung ADC after surgical resection as evaluated by the comprehensive and detailed histological diagnostic model according to the new IASLC/ATS/ERS classification; (2) the MP pattern was defined as MP predominant or containing an MP component; (3) disease-free survival (DFS) and/or overall survival (OS) should be evaluated in the study; and (4) the hazard ratio (HR) of DFS and/or OS was obtained through multivariate Cox regression analysis
The fixed effects meta-analysis showed that the DFS of MP component-positive patients was significantly worse than that of MP component-negative patients (HR 1.80, 95% confidence interval (CI) 1.14–2.85, I2 = 0%, P = 0.01) (Fig. 2)
Summary
Primary bronchial lung cancer is one of the most malignant tumours with the highest morbidity and mortality in China and the world, seriously endangering human health [1]. According to the recommendations of the new classification, the 5 main growth patterns (lepidic, acinar, papillary, micropapillary and solid) of invasive lung ADC should be recorded in 5% increments, and the pattern with the highest proportion determines the predominant subtype [4]. Many studies have reported the poor prognosis of lung ADC with the micropapillary (MP)-predominant subtype [8, 9]. Studies have shown that the MP predominant subtype of lung ADC is closely related to lymph node metastasis, vascular tumour thrombosis, visceral pleural invasion, and spread through air spaces (STAS) [10,11,12]. Two studies showed that the presence of an MP component does not suggest a poor prognosis for lung ADC [13, 14]. It is uncertain whether the presence of an MP component has equal prognostic power as the MP predominant subtype
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