Prognostic significance of karyotype at diagnosis in childhood acute lymphoblastic leukemia [corrected]

Acute lymphoblastic leukemia (ALL) is the most frequent childhood cancer. The disease is heterogeneous. The leukemic cells in childhood ALL patients show various karyotypic abnormalities, express diverse phenotypes, and respond variably to treatment. Identification of prognostic factors will make it possible to predict treatment outcome and to identify the patients that require different therapeutic approaches. The important prognostic implications of chromosome number and of the presence of several well defined structural chromosomal aberrations have been established by several groups. We analyzed 145 children with ALL at diagnosis for cytogenetic features. In 135 cases cytogenetic analysis was successful. Of these, 101 showed abnormal karyotype (70%). Structural chromosomal rearrangements were detected in 71 out of 135 cases investigated (53%), i.e. 71% of the cytogenetically abnormal cases. These cytogenetic findings were correlated with clinical outcome. In our series the ploidy of the karyotype appeared to be of prognostic importance. Our findings concerning karyotype, phenotype, and treatment outcome of this subgroup were in most cases in agreement with earlier reports from other investigators. We observed an increased risk for central nervous system relapse in childhood ALL patients with abnormalities involving the short arm of chromosome 12 in combination with pre-B or common ALL phenotype.