Serum neuron-specific enolase. A marker for responses to therapy in seminoma.

Neuron-specific enolase (NSE) was evaluated as a serum marker in 105 patients with testicular cancer and compared with the established tumor markers alphafetoprotein (AFP) and human chorionic gonadotropin (HCG). Increased serum NSE activity was measured in eight of 11 (73%) patients with metastatic seminoma. Serum NSE concentrations fell to within the normal range following chemotherapy. Localization of NSE in seminoma cells was demonstrated immunohistochemically. Only six of 40 (15%) patients with metastatic nonseminomatous germ cell tumors showed elevated serum NSE levels. AFP and HCG were both positive in 70% of patients in this group, and NSE determination gave no additional information. Serum NSE concentrations were normal in 53 of 54 testicular cancer patients after orchiectomy and there was no evidence of metastatic disease; only one had borderline NSE levels, indicating the specificity of serum NSE determination. NSE is a new marker of seminoma and its measurement may be of clinical value in monitoring chemotherapy in patients with metastatic seminoma.