Background: Monocyte chemotactic protein-1 (MCP-1) is a chemokine ligand that has been associated with aggressive behavior in breast and prostate cancer. The present study was performed to determine if there is a relationship between the expression of MCP-1 in papillary thyroid carcinoma (PTC) and factors indicative of aggressive behavior in this disease. Methods: The subjects of this study were 115 patients with PTC. MCP-1 expression was determined using a semiquantitative scoring system for immunohistochemical staining of MCP-1 in resected PTC samples. There were four levels of immunohistochemical staining intensity, and the population of cells that positively stained for MCP-1 was graded at four levels. The scores for the intensity of immunohistochemical staining for MCP-1 and for the percentage of cells that stained for MCP-1 were used to generate a range from 0 to 9 for scoring MCP-1 expression. Results: Positive staining for MCP-1 was observed in the cytoplasm of PTC cells and stroma cells in 79.2% of the specimens. Expression levels of MCP-1 in PTC cells were positively correlated with tumor size (p < 0.05) and lymph node involvement (p < 0.05). In addition, the expression of MCP-1 in PTC cells level was an independent predictive factor for recurrence of PTC in an analysis that included age, sex, tumor size, extrathyroidal infiltration, and lymph node involvement (p < 0.005). Conclusions: MCP-1 expression in PTC may stimulate the aggressive behavior of this tumor or it may be a marker for aggressive behavior. Previous reports with non-thyroid tumor cells favor the hypothesis that MCP-1 expression promotes aggressive behavior in PTC.
