Biology of neuroblastomas that were found by mass screening at 6 months of age in Japan

Background Mass screening (MS) of neuroblastoma has been carried out by measuring the urinary catecholamine metabolites in infants at the age of 6 months in Japan. We assessed the incidence of neuroblastoma that may be a target for MS by studying tumor biology. Procedure FISH on chromosome 1 and MYCN analysis was performed on 453 patients that were classified into three clinical groups (287 infants found by MS, 51 infants < 12 months diagnosed clinically, and 115 children ≥12 months diagnosed clinically). The relationship between the biological types of tumors and the clinical outcome was examined. Results Type 1 (trisomy 1 and normal MYCN), type 2 (disomy 1/tetrasomy 1 and normal MYCN), and type 3 (disomy 1/tetrasomy 1 and amplified MYCN) tumors were found in 88.2%, 10.5%, and 1.4% of infants found by MS, in 68.0%, 24.0%, and 8.0% of infants diagnosed clinically, and in 23.4%, 42.3%, and 34.2% of children diagnosed clinically ( P  < 0.001). Infants with type 1 tumors found by MS or diagnosed clinically had earlier stages of the disease ( P  < 0.0001 and P  = 0.0005) and better overall survival ( P  < 0.001 and P  = 0.005) than children with type 1 tumors diagnosed clinically. Infants with type 2 tumors found by MS, had earlier stages ( P  = 0.06 and P  < 0.0001) and better overall survival ( P  = 0.014 and P  < 0.001) than infants or children with type 2 tumors diagnosed clinically. All three clinical groups of patients with type 3 tumors had advanced stages and dismal prognoses. Conclusions About 12% of tumors found by MS showed unfavorable biological (types 2 and 3) characteristics. © 2005 Wiley‐Liss, Inc.