Creatine kinase BB: a new tumor-associated marker.

Creatine kinase isoenzyme BB (CK-BB) is found in the serum of patients with various types of cancer. Using both radioimmunoassay and agarose electrophoresis, we found abnormal amounts of this isoenzyme in the serum of 15 of 17 patients with untreated prostatic carcinoma. Among patients with other types of adenocarcinomas and metastatic disease, serum CK-BB was increased in most of those who were unresponsive to therapy. In benign or malignant prostate tissue and in malignant pleural effusions, cytoplasmic CK-BB as determined by immunoperoxidase staining was found in epithelial cells. Prostatic fluid had high concentrations of CK-BB, as did malignant, but not benign, pleural fluid supernates. We conclude that glandular epithelial cells contain CK-BB, which is released in benign and malignant states and may appear in higher concentrations in the circulation in malignant states. These conclusions are consistent with predictions we have made from a model experimental system concerning characteristics of possible tumor markers. The observations indicate a role for CK-BB as a tumor marker, particularly for adenocarcinoma of the prostate.