The features of PD-L1 expression in tumor stromal cells, peritumoral microvessels and isolated clusters of tumor cells in breast cancer tissue and their correlation with clinical and morphological characteristics of breast cancer

Abstract

Objective: to study the features of PD-L1 expression in tumor stromal cells, peritumoral microvessels, and isolated clusters of tumor cells in breast cancer (Bc) tissue and their correlation with the clinical and morphological characteristics of Bc.Material and Methods. The study included 158 patients with newly diagnosed invasive BC. PD-L1 expression was studied by immunohistochemistry. statistical analysis was performed using statistica 12.0 software.Results. PD-L1 expression in peritumoral microvessels occurred in 41.4 and 61.7 % of cases with t1–2 and T3–4 (p=0.020), and in 39.8 and 51.7 % of cases with N0–1 and N2–3 (p=0.008), respectively. In isolated clusters of tumor cells, the marker expression was observed in 28.0 and 52.5 % of cases in nodular and diffuse forms of BC (p=0.005); in 25.9, 39.3 and 66.7 % of cases at stages I–IIb, IIIa–IIIc and IV  (p=0.011); in 30.3, 26.2, 40.0 and 52.5 % of cases in T1, T2, T3 and T4 (p=0.040); and in 28.2 and 45.5 % of cases in N0–1 and N2–3 (p=0.030), respectively. Nuclear expression of PD-L1 was also detected in stromal cells, and was observed in 28.8 and 55.0 % of cases with nodular and diffuse forms of BC (p=0.003), in 17.6, 52.5 and 75.0 % of cases in early, locally advanced and metastatic BC (p<0.001), in 21.2, 28.7, 80.0 and 55.0 % of cases in T1, T2, T3 and T4 (p=0.002), in 21.7, 35.3, 51.4 and 55.0 % of cases with N0, N1, N2 and N3 (p=0.005), in 49.0 and 29.0 % of cases with negative and positive status of PR (p=0.014), in 30.3 and 52.8 % of cases with HER2-negative and HER2-positive BC status (p=0.014), respectively.Conclusion. The data indicate the relationship between PD-L1 expression and BC progression. The determination of PD-L1 expression in peritumoral microvessels and isolated tumor cell clusters, as well as nuclear expression of the marker, can be used to clarify the prognosis of the disease.