Monosomy 7 and Deletion 7q in Childhood AML. A Collaborative Study of 20 Study Groups

Monosomy 7 (−7) and deletion 7q [del(7q)] are rare in childhood AML and are considered to be associated with a poor outcome. We retrospectively analyzed data on 267 children with de novo AML or RAEB-T (PB or BM blasts > 20%) with −7 or del(7q) with or without additional cytogenetic aberrations (other). Patients were diagnosed between 1985 and 2003. Karyotypes showed −7 (n=90), −7 other (n=82), del(7q) (n=22), and del(7q) other (n=73). All 24 patients with RAEB-T had −7 +/− other. The median age at diagnosis was 7.6 years (range; 0–18.1) with no difference in age distribution between cytogenetic subgroups. The most common additional cytogenetic aberrations were inv(3)/t(3;3) in 19 patients (−7, n=17; del(7q), n=2) and favorable aberrations [t(8;21), inv(16), and t(15;17)] observed in 25 patients (−7, n=3; del(7q), n=22). The 5-year overall probability of survival for the whole group was 39%, SE=3%, and survival was higher in patients with del(7q) +/− other compared with −7 +/− other (52% vs. 30%). The survival of patients with del(7q) and favorable cytogenetic aberrations (n=22) was higher than that of other patients with del(7q) (75% vs. 46%, p=0.026). There was no significant difference in survival for patients with −7 and −7 other. Complete remission (CR) was obtained in 188 patients (−7 +/− other 62%; del(7q) +/− other 88%), of these, 67 received hematopoietic stem cell transplantation (HSCT) in CR1. There was no significant difference (Mantel-Byar test) in survival for patients who received HSCT in CR1 (49%, SE= 7%) and those who received chemotherapy only (51%, SE=5%, 54% for patients surviving at least the median time to HSCT). In conclusion childhood AML subgroups −7 and del(7q) differ in their associated cytogenetic aberrations and response to therapy.