SERUM NEURON-SPECIFIC ENOLASE AS A TUMOR-MARKER IN THE DIAGNOSIS AND FOLLOW-UP OF SMALL-CELL LUNG-CANCER

Serum samples for the determination of neuron-specific enolase (NSE) l evels were collected at diagnosis, after induction of chemotherapy and at relapse in order to assess the value of NSE in the diagnosis and m anagement of small-cell lung cancer (SCLC). At diagnosis, 47 of 64 pat ients with SCLC (73%) had abnormal NSE values (i.e. NSE >12.5 mu g/l). Mean NSE values were significantly higher in patients with extensive disease compared to limited disease. Patients with other malignancies or benign lung diseases presented with elevated NSE levels in approxim ately 15 and 4% of cases. Sensitivity, specificity and predictive valu e of positive results of NSE at diagnosis were 74, 83 and 71%, respect ively, for a cutoff value of 12.5 mu g/l. In responders mean NSE dropp ed significantly from 46.1 mu g/l before chemotherapy to 17.0 mu g/l a fter three cycles of chemotherapy. Nonresponders as a group showed a n onsignificant drop. At relapse mean NSE increased from 6.5 mu g/l at t he time of response to 51.9 mu g/l at the time of progression, but in 5 of the 18 evaluable patients normal levels persisted. Thus, evolutio n of NSE in patients receiving chemotherapy correlated well with tumor volume in patients who responded, but often failed to predict a thera peutic outcome in patients with apparently chemoresistant tumor (i.e. some nonresponders showed a decrease in NSE levels). A similar lack of correlation between NSE levels and tumor volume was seen at the time of relapse. We conclude that the determination of NSE levels is of dou btful utility in the diagnosis and follow-up of SCLC patients.