YKL‐40, a cellular glycoprotein isolated from the human osteosarcoma (OS) cell line MG63, is increased in the blood of patients with various types of cancer, and is found as an independent prognostic variable for survival. YKL‐40 is also present with variable intensity in the tumor cells of some cancer types, but survival results have been conflicting. The aim of this study was to investigate the tissue expression of YKL‐40 and its possible role as a predictive marker in patients with OS. Forty‐eight patients were included in the study. Diagnostic biopsies were analyzed by immunohistochemistry; YKL‐staining scores as well as CD14 and CD163 scores were determined, and survival data were determined statistically. A universal intense immunostaining for YKL‐40 was found in all tumor cells, but tumor cell/stroma ratio varied, and this ratio (%) served as staining score. Using 24% as mean score to divide the material, patients with tumors of high YKL‐40 score had a better survival than patients with low score (p = 0.05). YKL‐positive macrophages had no influence on the result. Unexpectedly and contrary to some other findings in cancer tissues, this study has shown a correlation between high YKL‐40 tumor cell/matrix ratio and longer overall survival in OS.
