A hospital-based case-control study of acute myeloid leukemia in Shanghai: analysis of personal characteristics, lifestyle and environmental risk factors by subtypes of the WHO classification.
OBJECTIVE
The objectives are (1) to investigate and identify potential risk factors (personal characteristics, lifestyle and environmental factors) of acute myeloid leukemia (AML), and (2) to explore the relationships between potential risk factors and AML subtypes according to the World Health Organization (WHO) classification of myeloid neoplasms.


METHODS
The investigation was a hospital-based case-control study consisting of 722 confirmed AML cases and 1444 individually gender-age-matched patient controls at 29 hospitals in Shanghai. A 17-page questionnaire was used to obtain information on: demographics, medical history, family history, lifestyle risk factors, employment history, residential history, and environmental and occupational exposures. Certain occupations of interest triggered a second questionnaire, which was occupation-specific and asked for more details about jobs, tasks, materials used and work environment. Risk estimates (odds ratios and 95% confidence intervals) were calculated using conditional logistic regression models.


RESULTS
Several potential risk factors of AML (all subtypes combined) and individual subtypes were identified; including low-level education, body mass index (BMI), blood transfusion, smoking, alcohol consumption, home or workplace renovation, living on a farm, planting crops, raising livestock or animals, employment as farm workers or in the agricultural industry, and exposures to insecticides or fertilizers. Some risk factors applied to all or several subtypes (such as low-level education and living on a farm), while others were limited to one or two specific subtypes (such as home/office renovation and acute promyelocytic leukemia). An inverse association was found between BMI and overall AML or the sub-category "AML not otherwise categorized", whereas a positive association between BMI and the subtype acute promyelocytic leukemia was detected. An unexpected finding was the association between the use of traditional Chinese medicines and a reduced risk of AML in general as well as several major subtypes.


CONCLUSIONS
The study identified a number of risk factors for AML in general as well as for some specific subtypes. Some of the risk factors were subtype-specific. The difference in risk by subtype underscores the importance of investigating the etiologic commonality and heterogeneity of AML by subtype in epidemiologic research.
Wong
Otto
O
Applied Health Sciences, San Mateo, CA 94401, USA. ottowong@aol.com
Harris
Fran
F
Yiying
Wang
W
Hua
Fu
F
D000328:Adult; D000368:Aged; D015992:Body Mass Index; D016022:Case-Control Studies; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000145:classification / Q000453:epidemiology / Q000209:etiology*; D008019:Life Style; D016015:Logistic Models; D008297:Male; D008516:Medicine, Chinese Traditional / Q000379:methods*; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects*; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014944:World Health Organization