Determination of creatine kinase isozymes in sera and tissues of patients with various lung carcinomas.

Three creatine kinase isozymes (CK-BB, CK-MB and CK-MM) were estimated by immunoassay in tumor tissues and in sera of patients with various lung carcinomas. CK-BB was increased in small cell carcinoma, but not in other lung carcinomas. CK-MM and CK-MB were not increased in any types of carcinoma. Serum CK-BB was increased in all types of lung carcinoma examined, while serum CK-MM and CK-MB were within normal limits in all patients. Serum CK-BB of healthy adults was estimated as 0.32 +/- 0.14 (mean +/- SD) ng/ml, ranging from 0.11-0.68 ng/ml. If CK-BB values above 1.0 ng/ml were considered abnormal, elevation occurred in 28/40 (70%) of patients with small cell carcinoma, 25/67 (37%) with adenocarcinoma, 21/51 (41%) with squamous cell carcinoma, 4/11 (36%) with other carcinoma of the lung and 10/42 (24%) with lung tuberculosis. Since serum CK-BB with lung cancer changed in parallel with the clinical course, this isozyme may be a marker for monitoring the clinical course, especially in small cell carcinoma of the lung.