High platelet-to-lymphocyte ratios in triple-negative breast cancer associates with immunosuppressive status of TILs

Abstract

Background: Rating lymphocytes (TILs) are a prognostic marker in breast cancer and high TIL infiltration correlates with better patient outcomes. Meanwhile, parameters involving immune cells in peripheral blood have also been established as prognostic markers. High platelet-to-lymphocyte ratios (PLRs) and neutrophil-to-lymphocyte ratios (NLRs) are related to poor outcomes in breast cancer, but their mechanisms remain unknown. To date, TILs and these parameters have been examined separately.

Methods: We investigated the relationship between TILs and the peripheral blood markers, PLR and NLR, in the same patients, using surgical specimens from 502 patients with invasive breast carcinoma without preoperative chemotherapy. For analysis of triple-negative breast cancer (TNBC) patient outcomes, 59 patients who received preoperative chemotherapy were also examined. For immune cell profiling, multiplexed fluorescent immunohistochemistry (mfIHC) of CD3, CD4, CD8, FOXP3 and T-bet, was conducted.

Results: A positive correlation between PLR and TIL was observed in TNBC (P = 0.013). On mfIHC, tumors in patients with high PLR and NLR contained more CD3⁺CD4⁺FOXP3⁺ T-cells (P = 0.049 and 0.019, respectively), while no trend was observed in CD8⁺ T-cells. TNBC patients had different patterns of outcomes according to TIL and PLR, with the TIL-high/PLR-low group having the lowest rate of disease relapse and death, and the longest distant metastasis-free and overall survivals, while the TIL-low/PLR-high group had the shortest survivals.

Conclusions: Our data suggest that the combination of PLR with TIL assessment may enable more accurate prediction of patient outcomes with TNBC.

Keywords: Multiplexed fluorescent immunohistochemistry; Platelet-to-lymphocyte ratio; Regulatory T-cells; Triple-negative breast cancer; Tumor-infiltrating lymphocyte.

Fig. 1

Relationships between tumor-infiltrating lymphocytes and platelet-to-lymphocyte ratio, and TILs and neutrophil-to-lymphocyte ratio. Relationships between tumor-infiltrating lymphocytes (TILs) and platelet-to-lymphocyte ratio (PLR), and TILs and neutrophil-to-lymphocyte ratio (NLR) (all log-transformed) are shown in (a) all patients, (b) luminal HER2-negative (Lum), (c) luminal HER2-positive (LumH), (d) human epidermal growth factor receptor 2 type (HER), and (e) triple-negative (TN) tumors. Green lines and light green areas indicate regression lines and 95% confidence intervals, respectively. “r” indicates the Pearson's correlation coefficient

Fig. 2

Relationships of T-cell lymphocyte infiltration and platelet-to-lymphocyte ratio. a Representative images of CD3⁺CD8⁺, CD3⁺CD4⁺T-bet⁺, and CD3⁺CD4⁺FOXP3⁺ T-cell detections. b and c Relationships between a variety of T-cell lymphocyte infiltrations and platelet-to-lymphocyte ratio (PLR). Assessments in (b) cancer and (c) stromal areas are separately indicated. White arrows indicate respective corresponding immune cells. Green lines indicate regression lines

Fig. 3

Kaplan–Meier curves of triple-negative breast cancer patients (n = 176) according to tumor-infiltrating lymphocytes (TILs) and platelet-to-lymphocyte ratios (PLRs). Patient outcomes according to patient groups, based on TIL and PLR are shown. Group 1, TIL-high/PLR-low (n = 31); Group 2, TIL-high/PLR-high (n = 43); Group 3, TIL-low/PLR-low (n = 60); and Group 4, TIL-low/PLR-high (n = 42). a Distant metastasis-free-survival (DMFS) and, c overall survival (OS) according to TILs. Dark blue and red lines indicate TIL-high patients (Groups 1 and 2), and TIL-low patients (Groups 3 and 4), respectively. b Comparison of DMFS and, d OS, according to the four patient groups