[Evaluation of serum S100ao protein in patients with renal cell carcinoma]

In order to evaluate the clinical significance of S100ao protein, we measured serum S100ao protein in 36 patients with renal cell carcinoma by EIA developed by Kimura et al. In addition, the distribution of S100ao protein was studied by the immunohistochemical method. Previous study demonstrated that mean level of serum S100ao protein in healthy volunteers was 203 +/- 107 pg/ml, therefore the cut off level was set to 524 pg/ml. The results obtained in this study were as follows: 1) The mean level of serum S100ao protein was 1162 +/- 2056 pg/ml, and its positive rate was 44% in 36 patients with renal cell carcinoma. When the patients were divided into 2 groups according to tumor stage, the mean level of serum S100ao protein in the high stage group was significantly higher than that in the low stage group (p less than 0.01). 2) In the sequential study of serum S100ao protein, patients with progressive disease showed a gradual increase in the level of serum S100ao protein while patients with no evidence of tumor showed a normal level of serum S100ao protein. 3) There was no correlation between the level of serum S100ao protein and the histological grade of renal cell carcinoma. 4) Immunohistochemical analysis (10 cases) showed that S100ao protein was observed in all of 10 renal cell carcinomas. Thus, the present study suggests that serum S100ao protein might be a useful clinical marker especially in monitoring patients with renal cell carcinoma.