Immunocyte density in parathyroid carcinoma is correlated with disease relapse

Purpose Parathyroid carcinoma (PC) is an endocrine malignancy with a poor prognosis. The tumour immune microenvironment is a critical factor influencing the outcomes of multiple cancer types. However, knowledge of the immune microenvironment in PC remains limited. Methods The intratumoural density of immunocytes and the Ki-67 index were evaluated immunohistochemically in 51 PC patient samples and were compared with clinicopathological features and parafibromin staining results. The Kaplan–Meier method and Cox proportional hazards analysis were used to estimate the effects of these variables on clinical outcomes. Results Intratumoural immunocyte density was not correlated with age, gender, urolithiasis, or palpation of a neck mass. The Ki-67 index was correlated with the intratumoural density of CD3 + cells ( P = 0.022) and CD8 + cells ( P = 0.021) and serum calcium levels ( P = 0.022). In the intratumoural area of primary foci, Kaplan–Meier method showed that the risk factors associated with recurrence/metastasis were a low density of CD3 + ( P = 0.017), CD8 + ( P = 0.019) and CD45 + cells ( P = 0.047), a high density of CD163 + cells ( P = 0.003) and a high Ki-67 index ( P = 0.004). Cox regression multivariate analysis revealed that CD163 + cell density (hazard ratio (HR) 16.19, 95% confidence interval (CI) 1.99—131.66; P = 0.009) and CD8 + cell density (HR 0.13, 95% CI 0.02—0.76, P = 0.024) were independent factors associated with PC relapse. Conclusion The immune microenvironment is an important factor influencing the relapse of PC. The intratumoural density of CD3 + , CD8 + , CD45 + , and CD163 + immunocytes was correlated with disease-free survival (DFS) in patients with PC. Immunotherapy based on T lymphocytes or tumour-associated macrophages may be a promising treatment strategy.