We assessed tumor cell DNA content (ploidy) and N-myc gene copy number as predictors of long-term disease-free survival in 298 children with neuroblastoma. Diploid tumor stem lines were identified in 101 patients (34%), clonal hyperdiploid abnormalities in 194 (65%), and hypodiploid stem lines in three (1%). In children with widely disseminated tumors at diagnosis (stage D), ploidy had a highly age-dependent influence on prognosis. Among infants (less than 12 months) treated with cyclophosphamide-doxorubicin, hyperdiploidy was closely associated with long-term disease-free survival (greater than 90% of cases), while diploidy invariably predicted early treatment failure (P less than .001). Similarly, in children 12 to 24 months of age who were treated with cisplatin-teniposide and cyclophosphamide-doxorubicin, diploidy uniformly predicted early failure, whereas half of the children with hyperdiploidy achieved long-term disease-free survival (P less than .001). There was no relationship between ploidy and treatment outcome in children older than 24 months with stage D tumors who had a very low probability of long-term disease-free survival (less than 10%). N-myc gene amplification was detected in 37 (25%) of the 147 tumors tested, with the remainder showing single-copy levels of the gene. N-myc gene amplification was more frequent in diploid than in hyperdiploid tumors (23 of 57 v 14 of 87, P = .001) and predicted a high likelihood of early treatment failure. In children younger than 2 years with disseminated neuroblastoma, tumor cell ploidy and N-myc gene copy number provide complementary prognostic information that will distinguish patients who can be cured on current regimens from those who require new treatment strategies.

GM-CSF may provide an antitumor effect that prolongs survival and disease-free survival in patients with stage III and IV melanoma who are clinically disease-free. These results support institution of a prospective, randomized clinical trial to definitively determine the value of surgical adjuvant therapy with GM-CSF in such patients.

We studied the relation between the DNA content of neuroblastoma cells and the response to therapy in 35 infants under one year of age with a diagnosis of neuroblastoma. Using flow cytometric techniques, we found that in 27 cases the primary malignant stem line consisted of neuroblasts with hyperdiploid DNA content, ranging from 1.07 to 2.42 times the finding in normal diploid cells. All remaining cases had diploid stem lines. Diploidy was more common in infants with clinical Stage D neuroblastoma (metastases beyond regional lymph nodes) than in those with other, less advanced stages: 6 of 10 as compared with 2 of 25 (P = 0.003). Of 17 evaluable patients with unresectable hyperdiploid tumors, 15 had complete responses and two had partial responses to cyclophosphamide and doxorubicin; six others with diploid tumors did not respond (P = 0.00001). We also found that each of the four infants with Evans' Stage IV-S neuroblastoma, an unusual form of disseminated neuroblastoma with a relatively good prognosis, had hyperdiploid tumor cells of clonal origin. We conclude that in neuroblastoma of infants, hyperdiploidy of tumor cells is associated with a better response to chemotherapy than is diploidy.