Clinical value of neuron specific enolase in small cell lung cancer

Abstract

Lung cancers are fast growing tumors with early metastatic spread and poor prognosis. Most primary lung tumors can be classified into four mayor histological types: squamous cell carcinoma, adenocarcinoma, large cell carcinoma and small cell lung cancer (SCLC). SCLC differs clinically and biologically from the other three histological types, which are all generally referred to as non small cell lung cancer (NSCLC). Thus, both SCLC and NSCLC represent heterogeneous groups. Enolase (2 phospho-D glycerate hydrolase, EC 4.2.1.11) exist as several dimeric isoenzymes (aa, ab, ag, bb, gg). The ag and gg enolase isoenzymes are also known as neuron specific enolase (NSE). They are produced in central and peripheral neurons and malignant tumors (SCLC, neuroblastomas, intestinal carcinoid). NSE is the leading tumor marker in SCLC. Release of NSE in serum in patients where histological evidence is absent may support a diagnosis of SCLC. NSE should not be used for screening purposes. NSE does not correlate with the localization of metastases and/or with brain metastases, although it correlates well with the clinical stage. High NSE concentrations reflect advanced tumor stage and suggest a bad prognosis. In patients with SCLC serum levels of NSE reflect the response to chemotherapy. Increasing tumor marker indicate progressive disease often before this is evident from imaging techniques. Measurement of NSE may be helpful; guideline recommendations for their proper use in differential diagnosis and in monitoring the efficacy of therapy have been proposed by EGTM.