Comparison of Calbindin D‐28k and S‐100 Protein B in Neuroblastoma as Determined by Enzyme Immunoassay

Levels of two calcium‐binding proteins, calbindin D‐28k (calbindin‐D) and S‐100 protein B (S‐100b), were measured by immunoassay in solid tumors obtained surgically from pediatric patients. Mean concentrations of calbindin‐D and S‐100b in 73 neuroblastomas (23 ganglioneuroblastomas and 50 neuroblastomas) were 10‐ or 25‐fold higher, respectively, than those in other types of solid tumors in pediatric patients (n=15). The mean tumor concentration of calbindin‐D in patients with neuroblastoma (n=73) was 25.1 ng/mg (range 0.20 to 317.0 ng/mg soluble protein, SE=6.26); that of S‐100b was 278.3 ng/mg (range 0.93 to 2521 ng/mg soluble protein, SE=71.7). The mean concentration of calbindin‐D (4.4 ng/mg soluble protein) was significantly (P < 0.05) lower in stage IV, the most advanced stage. The mean concentration of S‐100b (74.0 ng/mg soluble protein) was lower in patients with undifferentiated neuroblastomas (P < 0.01). Tumor levels of the two calcium‐binding proteins were not correlated in patients with neuroblastoma, but each was strongly correlated with outcome in patients with neuroblastoma. The evidence suggests that measurements of the calcium‐binding proteins calbindin‐D and S‐100b would be useful for evaluating the prognosis of patients with neuroblastoma.