Preexisting conditions in pediatric ALL patients: Spectrum, frequency and clinical impact.

The etiology of acute lymphoblastic leukemia remains undisclosed in the majority of cases. A number of rare syndromic conditions are known to predispose to different forms of childhood cancer including ALL. The present study characterized the spectrum and clinical impact of preexisting diseases in a cohort of ALL patients from Germany, Austria and Switzerland with a focus on genetic diseases predisposing to cancer development.Retrospective database and study chart review included all patients from Germany, Austria and Switzerland (n=4939) enrolled into multicenter clinical trial AIEOP-BFM ALL 2000 between July 1999 and June 2009. Patients enrolled into study AIEOP-BFM ALL 2009 - which was initiated subsequent to AIEP-BFM ALL 2000 - who were reported with a cancer prone syndrome or chromosomal abnormality were additionally included in this study to increase conclusiveness of observations.A total of 233 patients with at least one reported condition could be identified. The following conditions were reported in more than one patient: Gilbert's disease (n=13), neurofibromatosis type I (n=8), ataxia telangiectasia (n=8), thalassemia (n=7), Nijmegen Breakage syndrome (n=6), cystic fibrosis (n=4), glucose-6-phosphate dehydrogenase deficiency (n=4), Noonan syndrome (n=2), Klinefelter syndrome (n=2), alpha-1-antitrypsin deficiency (n=2), primary ciliary dyskinesia (n=2). Especially those syndromes with a known cancer predisposition (NF type I, Ataxia telangiectasia, Nijmegen Breakage syndrome etc.) were associated with certain general and ALL-related characteristics, high therapy-related toxicity and reduced survival.The spectrum of underlying diseases within ALL patients is dispersed. A small number of ALL patients are reported with cancer predisposition syndromes at initial diagnosis which are associated with high rates of therapy-related toxicity and a markedly reduced chance of survival. The true prevalence of these conditions within the ALL population remains unknown due to inapparent clinical presentation. A targeted clinical and/or genetic screening for certain diagnoses like NF type I, Ataxia telangiectasia or Nijmegen Breakage syndrome could identify patients who benefit from adjustment of antileukemic therapy or intensification of supportive care.