Serum creatine kinase-BB and small cell anaplastic carcinoma of the lung: two case reports.

Recent reports have suggested that serum creatine kinase isoenzyme BB (CK-BB) may be used as a tumor marker for a variety of malignancies, particularly prostatic carcinoma. Two cases of small cell anaplastic carcinoma of the lung (SCAC) had markedly contrasting levels of CK-BB by serum electrophoresis. Retrospective analysis of the index cases, and four additional autopsy cases of SCAC, included: 1) quantitation of CK-B in postmortem tumor and adjacent non-tumor lung tissue; 2) enzymatic and radioimmunoassay serum levels of CK-B; and 3) CK-B immunoperoxidase staining of tumor and non-tumor tissues for CK-B. Serum CK-BB is a non-specific tumor marker, but its presence, in whatever amount, should alert the clinician to the possibility of an associated malignancy, particularly SCAC or metastatic carcinoma.