Prognostic significance of cytogenetic abnormalities of chromosome arm 12p in childhood acute lymphoblastic leukemia: a report from the Children's Cancer Group.
BACKGROUND
The authors have determined the prognostic significance of cytogenetically detectable 12p abnormalities, which are frequent in children with acute lymphoblastic leukemia (ALL), in a large cohort of patients treated on risk-adjusted protocols of the Children's Cancer Group (CCG).


METHODS
The presence of an abnormal 12p was identified among 1880 children with newly diagnosed ALL; outcome was assessed by standard life table methods.


RESULTS
A total of 174 cases (9%) had cytogenetically detectable 12p abnormalities; the majority of cases had a balanced translocation, a del(12p), or an add(12p). In the overall cohort, event free survival (EFS) at 6 years was similar for patients with or without a 12p abnormality (76%, SD = 6%, vs. 75%, SD = 2%, respectively; P = 0.60). Among patients with pseudodiploidy, an abnormal 12p conferred improved outcome (P = 0.008; relative risk = 0.51; 95% confidence interval [CI], 0.31-0.85). There was a trend for improved EFS for those with abnormalities in both chromosome 12 homologues (P = 0.16; relative risk = 0.39; 95% CI, 0.10-1.55) and those with low hyperdiploidy (P = 0.07; relative risk = 0.44; 95% CI, 0.18-1.09). Among T-lineage ALL patients, there was a trend for worse outcome for abnormal versus normal 12p (P = 0.14; relative risk = 1.97; 95% CI, 0.78-4.93). There was no difference in EFS for the 12 patients with a dic(9;12) compared with patients lacking an abnormal 12p.


CONCLUSIONS
These data suggest that although a cytogenetically detectable 12p aberration is a favorable risk factor for children with ALL and pseudodiploidy, it is not prognostic for the overall group of pediatric ALL patients treated with contemporary therapies of the CCG.
Heerema
N A
NA
Department of Genetics, Hughes Institute, St. Paul, MN, USA.
Sather
H N
HN
Sensel
M G
MG
Lee
M K
MK
Hutchinson
R
R
Nachman
J B
JB
Lange
B J
BJ
Steinherz
P G
PG
Bostrom
B
B
Gaynon
P S
PS
Uckun
F M
FM
D000293:Adolescent; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D002869:Chromosome Aberrations; D025063:Chromosome Disorders; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment