Prognostic impact of tumor-associated macrophage infiltration in non-small cell lung cancer: A systemic review and meta-analysis

// Jiandong Mei 1, 2, * , Zhilan Xiao 1, 2, * , Chenglin Guo 1, 2 , Qiang Pu 1, 2 , Lin Ma 1, 2 , Chengwu Liu 1, 2 , Feng Lin 1, 2 , Hu Liao 1, 2 , Zongbing You 3 , Lunxu Liu 1, 2 1 Department of Thoracic Surgery, West China Hospital, Sichuan University, Chengdu 610041, China 2 Western China Collaborative Innovation Center for Early Diagnosis and Multidisciplinary Therapy of Lung Cancer, Sichuan University, Chengdu 610041, China 3 Department of Structural and Cellular Biology, Tulane University, New Orleans, LA 70112, USA * These authors contributed equally to this work Correspondence to: Lunxu Liu, email: lunxu_liu@aliyun.com Zongbing You, email: zyou@tulane.edu Keywords: clinicopathological characteristics, non-small cell lung cancer (NSCLC), prognosis, tumor-associated macrophages (TAMs) Received: February 24, 2016 Accepted: April 11, 2016 Published: April 28, 2016 ABSTRACT Tumor-associated macrophages (TAMs) are important components of cancer microenvironment. In the present study, we searched PubMed, Embase, Cochrane library and Web of Science to perform a meta-analysis of 20 studies including a total of 2,572 non-small cell lung cancer (NSCLC) patients, in order to determine the association between TAMs and NSCLC prognosis. The combined hazard ratio (HR) of 9 studies showed that the density of total CD68 + TAMs in the tumor islet and stroma was not associated with overall survival (OS) of the patients. However, the pooled HR of 4 studies showed that high density of CD68 + TAMs in the tumor islet predicted better OS, while the pooled HR of 6 studies showed that high density of CD68 + TAMs in the tumor stroma was associated with poor OS. A high islet/stroma ratio of CD68 + TAMs was associated with better OS. A high density of M1 TAMs in the tumor islet was associated with better OS, while a high density of M2 TAMs in the tumor stroma predicted poor OS. These findings suggest that, although the density of total CD68 + TAMs is not associated with OS, the localization and M1/M2 polarization of TAMs are potential prognostic predictors of NSCLC.