Disomy 1 with terminal 1p deletion is frequent in mass-screening-negative/late-presenting neuroblastomas in young children, but not in mass-screening-positive neuroblastomas in infants.

Abstract

The mass screening (MS) of neuroblastoma has been undertaken in Japan by measuring urinary catecholamine metabolites in infants at the age of 6 months. To clarify the biological characteristics of MS-positive (MS+) tumors in infants and MS-negative (MS-)/late-presenting tumors in young children, metaphase cytogenetic and/or interphase 2-color FISH analyses using terminal 1p and pericentromeric 1q probes were performed on 246 (186 MS+ and 60 MS-) patients with neuroblastomas. The 246 tumors were classified into 4 groups on the basis of the constitution of chromosome 1; 22 tumors had disomy 1 with no 1p deletion (Dis1Norm1p); 41 tumors had disomy 1 or tetrasomy 1, all with the 1p deletion (Dis1Del1p); 164 tumors had trisomy 1, pentasomy 1, or a mixed population of cells with trisomy 1 and cells with tetrasomy 1, none with 1p deletion (Tris1Norm1p); 19 tumors with the same copy numbers of chromosome 1 as the Tris1Norm1p group, had 1p deletion (Tris1Del1p). mycn amplification was absent in the Dis1Norm1p and Tris1Del1p groups, frequent in the Dis1Del1p group (24/41), and rare in the Tris1Norm1p group (3/164) (p < 0.0001). Event-free survival at 5 years was lowest [19.5%; 95% confidence interval (CI), 5.1-33.9] in the Dis1Del1p group, highest in the Tris1Norm1p (96.3%; 95% CI, 93.5-99.2) and Tris1Del1p (94.7%; 95% CI, 84.7-104.8) groups, and intermediate but varied (54.5%; 95% CI, 33.7-75.4) in the Dis1Norm1p group (p < 0.0001). Of the MS+ tumors, 90% were Tris1Norm1p or Tris1Del1p, and 55% of the MS- tumors were Dis1Del1p. The finding that the Dis1Del1p tumors were frequent in MS- but not in MS+ tumors suggests the limited efficacy of the MS program into reducing mortality from neuroblastoma.