DOPA metabolism in neuroblastoma

Blood plasma samples from 60 neuroblastoma patients prior to, during, and following treatment were studied for their content of circulating DOPA using a radioenzymatic assay. Normal values were established from children who were tumor-free or had other nonneurogenic tumors. The highest plasma DOPA concentration in tumor-free or nonneuroblastoma controls was 5.3 ng/ml with a mean of 2.15 ng/ml. Most neuroblastoma patients (28/31) with active disease had DOPA values above this level. Only one out of 30 "successfully" treated patients without evidence of disease was encountered with an abnormally high level. In treated patients, elevated values forewarned of impending clinical recurrence or persistent tumor. Cerebrospinal fluid DOPA levels in one patient with cerebral neuroblastoma were extraordinarily high and suggests that this assay may prove useful to distinguish neuroblastoma from other central neuroectodermal or metastatic tumors. Plasma DOPA appears to be a reliable predictive and diagnostic test for neuroblastoma.