Enolase is a glycolytic enzyme that catalyzes the conversion of phosphoenol pyruvate to 2-fosfoglicerate. It is found in several dimeric isoforms, which contain three immunologically different subunits: α, β and γ. Α subunit of enolase is found in various mammalian tissues, while the β subunit is found primarily in heart and skeletal muscle. Isoforms αγ and γγ, neuron-specific enolase constituting or γ-enolase is detected in increased amounts in neurons and neuroendocrine cells and tumors originating in these cells.
Thus NSE is a useful marker in the monitoring of patients with neuroendocrine tumors, especially small cell lung cancer and neuroblastoma.
Indications for determining NSE – monitoring and treatment of the disease in patients with neuroendocrine tumors and APUDomas.
Absolute Indications: small cell lung cancer (SCLC) and neuroblastoma.
Relative Indications: medullary thyroid carcinoma.
In small cell lung cancer Increased NSE concentrations are found in 60-81% of cases. There is a correlation between NSE values and the presence of brain metastases, but there is a good correlation with clinical stage (degree of extension of the disease). The lack of response to chemotherapy is associated with persistently elevated NSE levels, while in the cases of remission of the disease normal values are found in 80-96% of cases. NSE is an important prognostic marker, with a positive predictive value of 92%.
In neuroblastoma NSE elevated levels are found in approximately 62% of affected children, in close correlation with the clinical stage of the disease. In APUDomas NSE is elevated in 34% of cases.
Method – ELISA.
Reference values - 4-12 ng / mL.
Limits and interference:
NSE should not be used in cancer screening in asymptomatic patients. Increased levels of NSE can be found in some cases of brain tumors (glioma, meningioma) and renal cell carcinoma (localized or metastatic).
Elevated levels of NSE can appear in benign brain or lung.