MEETING REPORT Ionising Radiation And

Leukemia (1998) 12, 1319-1323 O 1998 Stockton Press All rinhts reserved 0887-6924/98 $12.00 MEETING REPORT Ionising radiation and leukaemia potential risky: review based on the workshop held during the 10th Symposium on Molecular Biology of Hematopoiesis and Treatment of Leukemia and Lymphomas at Hamburg, Germany on 5 July 1997 FE Alexander1 and MF Greaves2 l Department of Public Health Sciences, University of Edinburgh Medical School; and 2Leukaemia Research Fund Centre at the Institute of Cancer Research, Chester Beatty Laboratories, London, UK Unexplained clusters of childhood leukaemia have generated hood and then rises slowly with age from a trough in late concern that they may be causally related to environmental adolescence. Rates have remained relatively stable in the exposure to ionising radiation. The workshop provides in-depth recent past but show some population-specific variations. The examination of the aetiology of childhood leukaemia, patterns of clustering exhibited by cases and the influence of exposure distribution of subtypes differs markedly between adults and to ionising radiation. special attention has been focussed on children, with ALL representing a small minority of adult cases the EUROCLUS studv of clusterina of childhood leukaemia and but the majority of childhood cases. More subtle variations l monitoring of popul&ions expos& to contamination following between adults and children occur within the four broad the Chernobyl accident. There is insufficient evidence to con- groups including ALL. Thus the aetiology of ALL in children clude that environmental ionising radiation exposure is a and adults may differ.2 Leukaemia aetiology was considered causative agent for small clusters such as that reported in the vicinity of the Kriimmel nuclear facility by Dr Alexander (speaking in place of Professor Greaves), Pro- Keywords: childhood leukaemia; clusters; ionising radiation; com- fessor Gassman and Dr Zeeb. mon infections Leukaemias can be induced experimentally in animals by ionising radiation, chemicals and viruses. In domesticated animals (cats, cattle, chickens) leukaemia/lymphoma can occur Introduction at a high rate due to interplay between retroviruses, social conditions and genetic background. In humans, the same The workshop was conducted as an adjunct to a symposium group of causative factors are known to apply to particular on 'Molecular Biology of Hematopoiesis and Treatment of subtypes of the disease. Experimental leukaemia/lymphoma Leukaemias and Lymphomas' in Hamburg, 2-6 July 1997. A can be induced indirectly in animals by proliferative stress in key motivational factor was the intense level of scientific, pub- the immune system and at least one human lymphoid neo- lic health and community concerns regarding the 'Elbmarsch plasia (gastric lymphoma in adults) has a similar aetiology. At cluster' of childhood leukaemias.' Although the area con- present no more than a small proportion of all cases (perhaps cerned is geographically very close to a nuclear facility (the about 15%) can currently be attributed to known risk factors. Krummel nuclear power plant) the workshop started from the In a lecture focussing on adult leukaemias, Dr Zeeb premise that a broadly based scientific approach was appro- reminded the workshop that the factor most commonly linked priate and that this should consider other causes of leu- with leukaemia is ionising radiation. The elevated incidence kaemia~,other studies of clustering of childhood leukaemia, compared to the baseline is much higher in leukaemias than as well as other evidence of association between ionising radi- in other cancers, as evident from the study of atomic bomb ation and leukaemia. This view was endorsed by Dr Fritz Vah- survivors. Studies involving persons exposed to low level renholt, State Minister of the Environment who, in his wel- ionising radiation suffer from a number of methodological come, stressed the need to consider the evidence for problems. For workers in nuclear power plants, a slightly elev- involvement of infectious agents in the aetiology of, specifi- ated risk for leukaemia has been reported. Studies among cally, childhood leukaemia and the relevance that this might populations in proximity to nuclear power plants remain have to the Elbmarsch cases. inconclusive. Studies of populations exposed to relatively high levels of ionising radiation have usually been interpreted as providing firm evidence that ionising radiation can cause all Aetiology: current knowledge leukaemia cell-types apart from CLL; this view was, however, challenged by Dr Kellerer who, in a provocative lecture, ques- Leukaemias constitute about 5% of all malignancies in most tioned the strength of the evidence for ALL. In her talk on the populations. There are four main subtypes of leukaemia (acute aetiology of childhood leukaemia, Dr Alexander acknowl- lymphoblastic leukaemia (ALL); acute myeloid leukaemia edged an established causative role for exposure to ionising (AML); chronic lymphocytic leukaemia (CLL); and chronic radiation (eg from exposure to the atomic bomb, in utero X- myeloid leukaemia (CML)) that may not only differ in biologi- ray) but suggested that the proportion of cases explained in cal terms, but also in causal mechanisms. Incidence and mor- this way is likely to be small. tality rates generally increase with age with the exception of A large number of studies have confirmed an increased risk acute lymphoblastic leukaemia which peaks in early child- of (adult) leukaemia, particularly AML, among workers exposed to benzene. Occupational exposure to a number of other solvents and other chemicals may also increase risk. Correspondence: Dr FE Alexander, Dept of Health Science, University There is limited evidence that similar exposures (eg to ben- of Edinburgh Medical School, Teviot Place, Edinburgh, EH8 9AC, UK zene via parental smoking) may influence childhood AML. Received 14 April 1998, accepted 13 May 1998 Chemotherapy with alkylating agents for malignant tumours Leukemia (1998) 12, 1319-1323 o 1998 Stockton Press All rrehts reserved 08876924/98 $12.00 MEETING REPORT Ionising radiation and leukaemia potential risk$: review based on the workshop held during the 10th Symposium on Molecular Biology of Hematopoiesis and Treatment of Leukemia and Lymphomas at Hamburg, Germany on 5 July 1997 FE Alexander' and MF Greaves2 Department of Public Health Sciences, University of Edinburgh Medical School; and 2Leukaemia Research Fund Centre at the Institute of Cancer Research, Chester Beatty Laboratories, London, UK Unexplained clusters of childhood leukaemia have generated hood and then rises slowly with age from a trough in late concern that thev mav be causallv related to environmental adolescence. Rates have remained relatively stable in the exposure to ionishg rabiation. The workshop provides in-depth recent past but show some population-specific variations. The examination of theaetiology of childhood leukaemia, pattek of clusterina exhibited bv cases and the influence of exDosure distribution of subtypes differs markedly between adults and to ionising radiation. special attention has been focussed on children, with ALL representing a small minority of adult cases the EUROCLUS study of clustering of childhood leukaemia and but the majority of childhood cases. More subtle variations monitoring of populations exposed to contamination following between adults and children occur within the four broad the Chernobyl accident. There is insufficient evidence to con- groups including ALL. Thus the aetiology of ALL in children clude that environmental ionising radiation exposure is a and adults may differ.2 Leukaemia aetiology was considered causative agent for small clusters such as that reported in the vicinity of the KrIimmel nuclear facility by Dr Alexander (speaking in place of Professor Greaves), Pro- Keywords: childhood leukaemia; clusters; ionising radiation; com- fessor Gassman and Dr Zeeb. mon infections Leukaemias can be induced experimentally in animals by ionising radiation, chemicals and viruses. In domesticated animals (cats, cattle, chickens) leukaemia/lymphoma can occur Introduction at a high rate due to interplay between retroviruses, social conditions and genetic background. In humans, the same The workshop was conducted as an adjunct to a symposium group of causative factors are known to apply to particular on 'Molecular Biology of Hematopoiesis and Treatment of subtypes of the disease. Experimental leukaemia/lymphoma Leukaemias and Lymphomas' in Hamburg, 2-6 July 1997. A can be induced indirectly in animals by proliferative stress in key motivational factor was the intense level of scientific, pub- the immune system and at least one human lymphoid neo- lic health and community concerns regarding the 'Elbmarsch plasia (gastric lymphoma in adults) has a similar aetiology. At cluster' of childhood leukaemias.' Although the area con- present no more than a small proportion of all cases (perhaps cerned is geographically very close to a nuclear facility (the about 15%) can currently be attributed to known risk factors. Krummel nuclear power plant) the workshop started from the In a lecture focussing on adult leukaemias, Dr Zeeb premise that a broadly based scientific approach was appro- reminded the workshop that the factor most commonly linked priate and that this should consider other causes of leu- with leukaemia is ionising radiation. The elevated incidence kaemia~,other studies of clustering of childhood leukaemia, compared

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