[Determination of various tumor markers, with special reference to neuron-specific enolase in lung cancer]

Serum neuron-specific enolase (NSE) was measured in 23 patients with small cell lung cancer (SCLC) and 184 patients with non-small cell lung cancer (non-SCLC), both of which were untreated. Increased levels of serum NSE were observed in 82.6% (19/23) of SCLC, whereas 9.8% (18/184) of non-SCLC had positive results showing an overall positive rate of 17.9% (37/207) in lung cancer cases. In addition, the elevation of serum NSE levels in non-SCLC patients seemed to suggest poor prognosis. Elevated serum NSE levels returned to normal with either surgical resection of the tumor or response to chemotherapy, after which serum NSE levels were again raised to levels higher than the previous ones in cases of relapse or progression. The evaluation of serum NSE may be a useful marker for both diagnosis and monitoring of responsiveness to therapy as well as for recognition of relapse and progression in SCLC. Identification of NSE as assessed by immunohistochemical procedure employing the ABC method on formalin-fixed paraffin-embedded tissue sections in lung cancer cases of each histological type, showed that some materials from non-SCLC cases were positively stained despite the presence of normal serum NSE levels, and did not always parallel the serum levels. Among other various tumor markers determined, serum CA 19-9 had a relatively high positive rate of 38.2% (42/110) in adenocarcinoma of the lung.