Serum creatine kinase B subunit in patients with renal cell carcinoma.

We determined the serum levels of the creatine kinase B subunit (CK-B) by an enzyme immunoassay method in patients with renal cell carcinoma (RCC) and benign renal diseases. Eighteen of 76 patients with RCC (24%) had elevated serum CK-B levels. The positive rates were 29% in stage I, 13% in stage II, 15% in stage III, and 27% in stage IV. In all 9 patients whose serum CK-B levels were serially measured and had been elevated before operation, the CK-B levels were reduced to the normal range after nephrectomy. These findings indicate that serum CK-B is a useful biomarker for monitoring the clinical course for a limited number of RCC patients, but is not a marker for diagnosis and staging. Concentrations of CK-B in RCC tissues were significantly lower than those of normal kidney. A high rate of cell turnover in tumor tissues might entail the higher level of serum CK-B in patients with RCC.