Tumoral Densities of T-Cells and Mast Cells Are Associated With Recurrence in Early-Stage Lung Adenocarcinoma

Abstract

Introduction: Lung cancer is the deadliest cancer in the United States and worldwide, and lung adenocarcinoma (LUAD) is the most prevalent histologic subtype in the United States. LUAD exhibits a wide range of aggressiveness and risk of recurrence, but the biological underpinnings of this behavior are poorly understood. Past studies have focused on the biological characteristics of the tumor itself, but the ability of the immune response to contain tumor growth represents an alternative or complementary hypothesis. Emerging technologies enable us to investigate the spatial distribution of specific cell types within the tumor nest and characterize this immune response. This study aimed to investigate the association between immune cell density within the primary tumor and recurrence-free survival (RFS) in stage I and II LUAD.

Methods: This study is a prospective collection with retrospective evaluation. A total of 100 patients with surgically resected LUAD and at least 5-year follow-ups, including 69 stage I and 31 stages II tumors, were enrolled. Multiplexed immunohistochemistry panels for immune markers were used for measurement.

Results: Cox regression models adjusted for sex and EGFR mutation status revealed that the risk of recurrence was reduced by 50% for the unit of one interquartile range (IQR) change in the tumoral T-cell (adjusted hazard ratio per IQR increase = 0.50, 95% confidence interval: 0.27-0.93) and decreased by 64% in mast cell density (adjusted hazard ratio per IQR increase = 0.36, confidence interval: 0.15-0.84). The analyses were reported without the type I error correction for the multiple types of immune cell testing.

Conclusions: Analysis of the density of immune cells within the tumor and surrounding stroma reveals an association between the density of T-cells and RFS and between mast cells and RFS in early-stage LUAD. This preliminary result is a limited study with a small sample size and a lack of an independent validation set.

Keywords: Adenocarcinoma; Lung cancer; Mast cells; Recurrence; T-cells.

Figure 1

Consort Diagram of patient inclusion. mxIHC, multiplexed immunohistochemistry; TMA, tissue microarray; VUMC IRB, Vanderbilt University Medical Center Institutional Review Board.

Figure 2

mxIHC staining of tumor punches allows spatially resolved cell identification. (A) Composite staining images are collected using the Vectra spectral imaging system. (B) Each cell’s phenotype was determined from the staining intensities so that a phenotype for each cell can be assigned to a specific location. Each dot represents one cell, and the color indicates the cell phenotype. (C) The distribution of cell types is used to segment tumor (red), stroma (green), and nontissue (blue) regions. HTX, hematoxylin; mxIHC, multiplexed immunohistochemistry.

Figure 3

Kaplan-Meier survival curves of recurrence-free-survival of four groups on the basis of quartile of cell density distribution in the early stage. (A) Tumoral T-cell density—group 1: (3.24–34.8), group 2: (34.8–65.56), group 3: (65.56–112), group 4: (112–370.6) per mm² of tumor tissue. (B) Tumoral mast cell density—group 1: (0–0.84), group 2: (0.84–2.8), group 3: (2.8–7.52), group 4: (7.52–134.96) per mm² of tumor tissue. HR represented as HR per IQR increase in cell density on the basis of the univariate Cox model. Adj. HR stood for the adjusted hazard ratio on the basis of the multivariable Cox model adjusted for sex and EGFR mutation status. Adj., adjusted; CI, confidence interval; HR, hazard ratio; IQR, interquartile range; RFS, recurrence-free survival.