Published online 2 June 2008
Haematologica, Vol 93, Issue 8, 1262-1263 doi:10.3324/haematol.12831
Copyright © 2008 by Ferrata Storti Foundation
Acute leukemia in children with Downs syndrome: the importance of population based study
Rebecca James1,2,
Tracy Lightfoot1,
Jill Simpson1,
Anthony V. Moorman3,
Eve Roman1,
Sally Kinsey2 on behalf of the UK Child Cancer Study Investigators
1 Epidemiology & Genetics Unit, Department of Health Sciences, University of York, UK
2 St James University Hospital, Leeds, UK
3 Northern Institute for Cancer Research, University of Newcastle, UK
Correspondence: Rebecca M. James, Epidemiology & Genetics Unit, Department of Health Sciences, University of York, Heslington, York, YO10 5DD UK. Phone: international +440.1904321893. Fax: international +44.1904321899. E-mail:beki.james{at}egu.york.ac.uk
Key words: acute leukemia, acute myeloid leukemia, myelodysplasia, myeloproliferative disorders, Downs syndrome.
The association between Downs syndrome (DS) and acute leukemia is well documented.1–3 However, most information derives from retrospectively compiled patient series or treatment trials, which may not represent the general DS population. We report cases of acute leukemia and DS collected in the UK Childhood Cancer Study (UKCCS), a national population based case-control study. Data were gathered on all children aged 0–14 years diagnosed with acute leukemia between 1991 and 1996, irrespective of trial entry. Detailed diagnostic information on all cases was obtained from multiple sources, including: the Medical Research Council; UKCCSG; the National Registry of Childhood Tumours; the individual treating consultant; and hospital records. In addition, detailed cytogenetic information on trial and non-trial cases was obtained from the Leukaemia Research Cytogenetics Group. Molecular diagnostic information on patients with acute lymphoblastic leukemia (ALL) was provided by the central reference laboratory at the Leukaemia Research Fund Centre, Institute of Cancer Research. Details of the conduct and ethical approval of the UKCCS are described in full elsewhere.4
In total 1,709 children with acute leukemia enrolled in the UKCCS (Table 1). Of these, 14(6%) of the 248 with AML, and 34(2%) of the 1,461 with ALL, also had DS. Trial uptake was significantly lower for children with DS: 32/48 (67%) children with DS were in trials compared with 1,468/1,709 (86%) of non-DS cases (p<0.01). Entry was lowest for children with DS-AML: with only 8/14 (57%) in trials.
We also report the striking finding that the increase in AML
incidence in DS was confined to FAB M6 and M7 sub-types; no
other FAB types were observed. Eleven (79%) of the DS-AML cases
were M7 and 3 were M6. Importantly this was not apparent initially
when the provisional diagnoses recorded by the treating hospital
were considered. However, following panel review for the MRC
AML 10 trial, 6 of the DS-AML cases initially diagnosed at the
treating hospital and recorded for trial and study purposes
as AML FAB M0 (4 cases), M1 (1 case) and M2 (1 case) were reclassified
as AML FAB M7 (4 cases) and M6 (2 cases). The high number of
reclassifications prompted review of the non-trial cases of
DS-AML. These comprised 5 cases of AML FAB M7 and one case of
AML FAB M6. All 6 diagnoses remained the same after review.
In contrast, taken together, M6 and M7 accounted for only 18
(8%) of non-DS AML (
p<0.001). The mean age at diagnosis of
AML was significantly lower in DS children: 2.2 years (95% CI:1.5–3.0)
compared with 6.7 years (95%CI:6.1–7.4;
p<0.001). Interestingly,
the average age at diagnosis of the 18 non-DS children with
AML M6 or M7 was only 3.2 years (95% CI:1.1–5.4) - comparable
with DS-AML. Cytogenetic profiles in these DS-AML cases were
consistent with previous reports (3;5;6). Typically, the favorable
translocations associated with non-DS AML, namely t(8;21), t(15;17),
inv(16), and t(1;22) typically associated with AML FAB M7, were
absent. Instead, a variety of unbalanced translocations were
seen: +8 in 5/14(36%) DS-AML; del(6q) in 2/14(14%); +11 in 1/14(7%)
and +21 in 1/14(7%) DS-AML cases. Interestingly, both cases
of del(6q) occurred in non-trial patients, emphasizing the importance
of population based analysis.
We confirm that B-cell precursor ALL (BCP-ALL) is the predominant form of leukemia observed in DS,3,7 occurring in 27/34 (79%) cases of DS-ALL compared with 1,067/1,427 (74%) cases of non-DS ALL. T-cell ALL, although reported, is extremely rare. There were no cases of proB or T-cell DS-ALL in our study. Age at diagnosis for DS- ALL and non-DS ALL were similar and the difference was not statistically significant. Whilst ML-DS is a specific entity, ALL in DS appears to be as heterogeneous as ALL in non-DS children. High hyperdiploidy (>50 chromosomes), a good-risk prognostic feature, appears underrepresented occurring in 1/27 (4%) cases. Testing for the most frequent chromosomal abnormality in childhood ALL, the ETV6-RUNX1 fusion resulting from t(12;21), was not standard in the study period. Specific chromosomal translocations associated with adverse outcomes in childhood ALL: 11q23/MLL translocations; t(9;22); and t(1;19) were absent in DS cases. However, the numbers are small. The finding of 5/27 (19%) cases with loss of 9p is interesting; it has been suggested elsewhere that it might play a significant role in the pathogenesis of DS-ALL.8 Two of these were in non-trial cases.
An excess of AML FAB M7 is well documented in DS: it is a unique disease associated with a pathognomonic mutation of GATA1.9 This report supports the separate pediatric WHO classification of myeloid leukemia of DS (ML-DS).10 It is notable that subtypes were reclassified in 6/14(43%) cases of DS-AML. Unfortunately, this does not appear to be reflected in an earlier report of DS cases in the MRC AML 10 and 12 trials,11 which appears to rely on the initial classifications, highlighting the importance of ensuring data is as comprehensive and up to date as possible. Here, the final AML subtypes were exclusively FAB M6 and M7. Although an apparent excess of AML M6 has also been reported, the association is not so clearly described.
A report considering trial cases alone for this period would have missed a third of all cases of acute leukemia in DS, and almost half of all cases of AML in DS. The relatively low entry of children with DS into trials limits the utility of reports solely derived from trials, emphasizing the need for a population based approach until trial entry rates have improved. Reports suggest that these are increasing, reflecting a growing recognition that children with DS may be successfully treated with intensive chemotherapy and in the context of a trial. There is a pressing need for a collaborative effort to gather data prospectively on all children with DS. The Children with Downs Syndrome Study (www.cdss.org.uk) is an observational cohort study set up specifically to address this need and will enable determination of the baseline characteristics of all children with DS. Furthermore, until trial entry improves, a population based approach is also imperative for the study of children with both DS and leukemia.

Acknowledgments
the United Kingdom Childhood Cancer Study is sponsored and administered
by the Leukaemia Research Fund. The Study was conducted by twelve
teams of investigators (ten clinical and epidemiological and
two biological) based in university departments, research institutes
and the National Health Service in Scotland. The work is co-ordinated
by a Management Committee. It is supported by the Childrens
Cancer and Leukaemia Group of pediatric oncologists and by the
National Radiological Protection Board. Financial support has
been provided by the Cancer Research Campaign, the Imperial
Cancer Research Fund, the Leukaemia Research Fund, and the Medical
Research Council through grants to their units; by the Leukaemia
Research Fund, the Department of Health, the Electricity Association,
the Irish Electricity Supply Board (ESB), the National Grid
Company plc, and Westlakes Research (Trading) Ltd through grants
for the general expenses of the study; by the Kay Kendall Leukaemia
Fund for the associated laboratories studies and by the
Foundation for Children with Leukaemia for the study of electric
fields. We would like to thank the Childrens Cancer and
Leukaemia Group (CCLG) (formerly the UK Childhood Leukaemia
Working Party), the Clinical Trial Service Unit (University
of Oxford) and the Birmingham Clinical Trials Unit (University
of Birmingham) for data on trial patients. We would like to
thank the members of the UK Childhood Cancer Study Group for
their support and staff of local hospitals, general practitioners,
general practice staff and UKCCS interviewers and technicians.
We would especially like to thank the families of the children
included in the study, without whom this investigation would
not have been possible

References
- Hill DA, Gridley G, Cnattingius S, Mellemkjaer L, Linet M, Adami HO, et al. Mortality and cancer incidence among individuals with Down syndrome. Arch Intern Med 2003;163:705-11.[Abstract/Free Full Text]
- Hasle H, Clemmensen IH, Mikkelsen M. Risks of leukaemia and solid tumours in individuals with Downs syndrome. Lancet 2000;355:165-9.[CrossRef][Web of Science][Medline]
- Zeller B, Gustafsson G, Forestier E, Abrahamsson J, Clausen N, Heldrup J, et al. Acute leukaemia in children with Down syndrome: a population-based Nordic study. Br J Haematol 2005;128:797-804.[CrossRef][Web of Science][Medline]
- UK Childhood Cancer Study Investigators. The United Kingdom Childhood Cancer Study: objectives, materials and methods. UK Childhood Cancer Study Investigators. Br J Cancer 2000;82:1073-102.[CrossRef][Web of Science][Medline]
- Lange BJ, Kobrinsky N, Barnard DR, Arthur DC, Buckley JD, Howells WB, et al. Distinctive demography, biology, and outcome of acute myeloid leukemia and myelodysplastic syndrome in children with Down syndrome: Childrens Cancer Group Studies 2861 and 2891. Blood 1998;91:608-15.[Abstract/Free Full Text]
- Creutzig U, Ritter J, Vormoor J, Ludwig WD, Niemeyer C, Reinisch I, et al. Myelodysplasia and acute myelogenous leukemia in Downs syndrome. A report of 40 children of the AML-BFM Study Group. Leukemia 1996;10:1677-86.[Web of Science][Medline]
- Whitlock JA, Sather HN, Gaynon P, Robison LL, Wells RJ, Trigg M, et al. Clinical characteristics and outcome of children with Down syndrome and acute lymphoblastic leukemia: a Childrens Cancer Group study. Blood 2005;106:4043-9.[Abstract/Free Full Text]
- Forestier E, Izraeli S, Beverloo B, Haas O, Pession A, Michalova K, et al. Cytogenetic features of acute lymphoblastic and myeloid leukemias in pediatric patients with Down syndrome - an iBFM-SG study. Blood 2008;111:1575-83.[Abstract/Free Full Text]
- Wechsler J, Greene M, McDevitt MA, Anastasi J, Karp JE, Le Beau MM, et al. Acquired mutations in GATA1 in the megakaryoblastic leukemia of Down syndrome. Nat Genet 2002;32:148-52.[CrossRef][Web of Science][Medline]
- Hasle H, Niemeyer CM, Chessells JM, Baumann I, Bennett JM, Kerndrup G, et al. A pediatric approach to the WHO classification of myelodysplastic and myeloproliferative diseases. Leukemia 2003;17:277-82.[CrossRef][Web of Science][Medline]
- Rao A, Hills RK, Stiller C, Gibson BE, de Graaf SS, Hann IM, et al. Treatment for myeloid leukaemia of Down syndrome: population-based experience in the UK and results from the Medical Research Council AML 10 and AML 12 trials. Br J Haematol 2006;132:576-83.[CrossRef][Web of Science][Medline]
This article has been cited by other articles:

|
 |

|
 |
 
A. C. Xavier, Y. Ge, and J. W. Taub
Down Syndrome and Malignancies: A Unique Clinical Relationship: A Paper from the 2008 William Beaumont Hospital Symposium on Molecular Pathology
J. Mol. Diagn.,
September 1, 2009;
11(5):
371 - 380.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
I. Ganmore, G. Smooha, and S. Izraeli
Constitutional aneuploidy and cancer predisposition
Hum. Mol. Genet.,
April 15, 2009;
18(R1):
R84 - R93.
[Abstract]
[Full Text]
[PDF]
|
 |
|