Concomitant monitoring of serum neuron-specific enolase and creatine kinase BB in small cell lung cancer.

Serum neuron-specific enolase (NSE) and serum creatine kinase isoenzyme BB (CK-BB) were measured in 43 small cell lung cancer (SCLC) patients. The overall sensitivity of NSE (greater than 12.5 ng/ml) was 65%; in limited disease (LD) 48% and in extensive disease (ED) 100%. CK-BB was detected in 14 patients (32%); the sensitivity was 17% in LD and 64% in ED. During treatment NSE declined or stabilized to normal level in LD together with objective response in 75% (21/28), and rose again with progression in 28% (6/21). CK-BB fell to normal in all 5 patients with LD, in 3 of them with objective response. In ED elevated NSE and CK-BB declined to normal with objective response in 73% (8/11) and in 25% (2/8) of the evaluable patients respectively. We conclude that serum NSE is a potential marker for staging and response monitoring in SCLC, but that CK-BB gives additional information of limited value.