Serial determination of serum neuron-specific enolase in patients with neuroblastoma and other pediatric tumors

The importance of determination of serum neuronspecific enolase (NSE) in patients with neuroblastoma has been emphasized by several authors. However, the specificity and sensitivity of NSE have not yet been well studied in tumors of infancy and childhood, nor is the role of serial determination of NSE in monitoring these patients fully understood. Concentrations of serum NSE were determined by a newly developed radioimmunoassay technique in 241 samples from 111 patients. NSE was also assayed in sera of nude mice bearing human pediatric tumors (16 samples), as well as in 30 tumor specimens. Eighty-two serum samples from 19 patients with neuroblastoma all showed NSE values (mean 120.2 ng/mL, range 16.2 to 722.0 ng/mL) elevated beyond the upper border of the normal range (14.6 ng/mL), even though four of the 19 patients had normal urinary excretion of 3-methoxy-4-hydroxymandelic acid (VMA) and 3-methoxy-4-hydroxyphenylacetic acid (HVA). Twelve of these patients were monitored with serial NSE determinations, and their serum NSE were found to correlate well with the tumor burden, but were transiently modified by chemotherapeutically induced cell death. All 68 samples from nine patients, free of neuroblastoma at assessment, showed NSE values within the normal range. Thirteen of 25 patients with tumors other than neuroblastoma, however, showed serum NSE values mildly elevated beyond the upper border of the normal range (mean of the 25 patients 36.7 ng/mL, range 5.0 to 234.0 ng/mL). Results from our nude mouse study and from NSE analysis of the tumor extracts paralleled the clinical results. We conclude that NSE is not so specific as it was considered previously, but it is a useful clinical marker for neuroblastoma because of its positivity and sensitivity.