Tumor-infiltrating lymphocytes and tumor-associated macrophages as potential predictors of lymph node metastases in major salivary gland cancers

PURPOSE: The purpose of this study is to define if tumor-infiltrating lymphocytes (TILs) and tumor-associated macrophages (TAMs) could represent potential predictors of lymph node metastases (LNM) in salivary gland cancers (SGC). METHODS: A selected number of immunohistochemical markers related to TILs (CD3, CD4, CD68, and FOXP3) and TAMs (CD68 and CD163) were investigated on major salivary gland cancers. TIL and TAM densities were measured on digital images using the open-source QuPath both in the tumor interior (TI) and invasive margin (IM). Correlation with pathologic N classification and follow-up clinical data was investigated. RESULTS: A total of 25 consecutive patients (men: 11; median age: 62.0) were included. Densities of CD3+ IM (OR = 7.7, 95% CI 1.2–51.2), CD8+ TI (OR = 7.7, 95% CI 1.2–51.2), CD8+ IM (OR = 7.7, 95% CI 1.2–51.2), FOXP3+ TI (OR = 24.0, 95% CI 2.2–255.9), CD68+ TI (OR = 7.7, 95% CI 1.2–51.2), and CD163+ IM (OR = 7.7, 95% CI 1.2 – 51.2), and the Immunoscore CD8/CD3 (OR = 1.9, 95% CI 1.1–3.4) were significantly associated with LNM (p < 0.05). CD3+ TI density was significantly associated with tumor recurrence and death (HR = 5.8, 95% CI 1.5–22.6; p < 0.05). CONCLUSION: A high density of specific TIL and TAM subpopulations might be correlated with a higher probability of LNM in SGC.