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/

The mass screening (MS) of neuroblastoma has been undertaken in Japan by measuring urinary catecholamine metabolites in infants at the age o f 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 Ip and pericentromeric Iq probes were performe d on 246 (186 MS+ and 60 MS-) patients with neuroblastomas. The 246 tu mors were classified into 4 groups on the basis of the constitution of chromosome I; 22 tumors had disomy I with no Ip deletion (Dis1Norm Ip ); 41 tumors had disomy I or tetrasomy I, all with the Ip deletion (Di s1DelIp); 164 tumors had trisomy I, pentasomy I, or a mixed population of cells with trisomy I and cells with tetrasomy I, none with Ip dele tion (TrisINormIp); 19 tumors with the same copy numbers of chromosome I as the TrisINormIp group, had Ip deletion (TrisIDelIp). mycn amplif ication was absent in the DisINormIp and TrisIDelIp groups, frequent i n the DisIDelIp group (24/41), and rave in the Tris I Norm Ip 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 Dis I Del I p group, hi ghest in the Tris I Norm I p (96.3%; 95% CI, 93.5-99.2) and Tris I Del I p (94.7%; 95% CI, 84.7-104.8) groups, and intermediate but varied ( 54.5%; 95% CI, 33.7-75.4) in the DisINormIp group (p < 0.0001), Of the MS+ tumors, 90% were TrisINormIp or TrisIDelIp, and 55% of the MS- tu mors were DisIDelIp, The finding that the DisIDelIp tumors were freque nt in MS- but not in MS+ tumors suggests the limited efficacy of the M S program into reducing mortality from neuroblastoma. (C) 1999 Wiley-L iss. Inc.