Overweight, obesity and risk of haematological malignancies: a cohort study of Swedish and Finnish twins.
BACKGROUND
Obesity is related to an increased risk of several forms of cancer. However, findings from studies on haematological malignancies are inconsistent.


METHODS
We used prospectively collected data from two Swedish twin cohorts and the Finnish Twin Cohort (in total 70,067 persons) to study the effects of overweight and obesity on the development of leukaemia, non-Hodgkin lymphoma, Hodgkin's lymphoma and myeloma. The cohorts were followed from baseline through 2002 (Sweden) and through 2004 (Finland).


RESULTS
We found a risk increase of myeloma with a relative risk (RR) of 2.1 (95% confidence interval [CI] 1.1-3.7) among obese persons, a RR of 2.5 (1.0-6.2) for chronic myeloid leukaemia and a RR of 2.7 (0.8-9.6) for acute lymphoblastic leukaemia among overweight persons as compared to normal-weighted ones.


CONCLUSIONS
Our results add further evidence suggesting that overweight and obesity may have an impact on some haematological malignancies, in particular myeloma.
Söderberg
Karin C
KC
The Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-171 77 Stockholm, Sweden. Electronic address: Karin.Soderberg@ki.se.
Kaprio
Jaakko
J
Department of Public Health, University of Helsinki, Finland; Department of Mental Health and Alcohol Research, National Public Health Institute, Helsinki, Finland and The Institute for Molecular Medicine, Helsinki, Finland.
Verkasalo
Pia K
PK
Department of Environmental Health, National Public Health Institute, Kuopio, Finland.
Pukkala
Eero
E
Finnish Cancer Registry, Institute for Statistical and Epidemiological Cancer Research, Helsinki, Finland.
Koskenvuo
Markku
M
Department of Public Health, University of Helsinki, Finland.
Lundqvist
Ellen
E
The Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-171 77 Stockholm, Sweden.
Feychting
Maria
M
The Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-171 77 Stockholm, Sweden.
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005387:Finland; D019337:Hematologic Neoplasms / Q000209:etiology*; D006801:Humans; D007938:Leukemia / Q000209:etiology; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000209:etiology; D009765:Obesity / Q000150:complications; D050177:Overweight / Q000150:complications*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012306:Risk; D012737:Sex Factors; D013548:Sweden