Prognostic Analysis of NSCLC Based on the Tumor-associated Macrophages, Tumor Neo-vessels and PD-L1 Expression in Tumor Microenvironment

Background Tumor microenvironment is a complex and dynamic community, which plays a crucial role in tumor progression via the co-evolution of cancer cells and tumor stroma. Among them, tumor-associated macrophages (TAMs) and tumor neo-vessels are two key components in the tumor microenvironment during cancer invasion. In addition, programmed cell death ligand 1/programmed cell death ligand 1 (PD-1/PD-L1) also plays an important role in tumorigenesis and development, and the clinical strategies to block PD-1/PD-L1 pathway could have great benefits for cancer patients. This study was aimed at analyzing the quantitative expression and prognostic significance of TAMs, tumor neo-vessels and PD-L1 in tumor microenvironment and exploring the relations between the expression of above components with the patients' prognosis of non-small cell lung cancer (NSCLC). Methods Clinico-pathological data and surgical specimens of 92 patients with NSCLC were collected, and immunohistochemistry was used to stain the expression of TAMs, tumor neo-vessels and PD-L1 on tumor tissue and peri-tumor tissues. The inverted microscopy was used to take pictures and Image-pro Plus 6.0 software was used for quantitative analysis. The clinicopathological characteristics and overall survival (OS) were analyzed. Results The median OS of 92 NSCLC cases was 22.5 month. The expression of TAMs, tumor neo-vessels and PD-L1 in tumor tissue and peri-tumor tissues were not statistically significant (P>0.05). According to the cutoff of above key three components in tumor microenvironment, all the cases could be classified into high, middle and low expression groups. The survival analysis demonstrated that the OS in high expression group of TAMs (P=0.016) and PD-L1 (P=0.002) was shorter than the other two groups, respectively, with statistical significance. The OS in high tumor neo vessels group was shorter than the other two groups. However, there was no statistical significance between these three group (P=0.626). Combined with above the three components, all the cases could be classified into low, middle and high density groups. The survival analysis demonstrated that the median OS of combined high density group was shorter than the other two groups (P=0.001). Multivariate analysis by Cox regression indicated that pathological type, TAMs and PD-L1 expression were the independent prognostic factors. Conclusions The key components of TAMs and PD-L1 in tumor microenvironment are closely related to the prognosis of NSCLC patients.