YKL-40 is an inflammation-associated glycoprotein supposed to have a role in cell survival and angiogenesis. Renal cell carcinoma (RCC) is characterized by varying prognosis and risk of relapse after a disease-free period of years. Prognostic markers are critically needed. This study investigated whether YKL-40 could be a useful biomarker in RCC patients.Blood samples from 82 patients with RCC were collected at the time of diagnosis and 3, 5 and 9 months and 2 and 3 years after nephrectomy. YKL-40 levels were determined by enzyme-linked immunosorbent assay. Survival of patients and relapse of RCC were followed up to 15 years.Circulating YKL-40 levels were increased in patients with metastatic RCC at the time of diagnosis (median 115.7 ng/ml, interquartile range 61.0-221.6 ng/ml). Among patients primarily diagnosed with non-metastatic RCC, baseline YKL-40 levels were significantly higher in patients who experienced a relapse during follow-up (103.7, 59.3-242.0 ng/ml) than in patients without relapse (50.6, 33.8-97.1 ng/ml). High baseline YKL-40 was highly associated with poor prognosis in RCC: in age-adjusted univariate analysis, YKL-40 over 120 ng/ml (highest tertile) predicted over five-fold mortality in 5 years, and in multivariate analysis high YKL-40 remained a statistically significant independent risk factor for 5 and 15 year survival.Increased circulating YKL-40 levels were significantly associated with poor survival in patients with RCC. The results suggest YKL-40 as a useful novel biomarker in evaluating prognosis and relapse risk in RCC, being especially beneficial in patients primarily diagnosed with non-metastatic RCC.
