Obesity over the life course and risk of acute myeloid leukemia and myelodysplastic syndromes

Background: Overweight and obesity are known risk factors for a number of cancers, with recent evidence suggesting that risk of hematologic cancer is also increased in obese individuals. We evaluated associations between body mass index (BMI) at differing time points during the life course in population-based case control studies of acute myeloid leukemia (AML) and myelodysplatic syndromes (MDS). Methods: Cases were identified by the Minnesota Cancer Surveillance System. Controls were identified through the Minnesota State driver's license/identification card list. BMI was calculated using self-reported height and weight at ages 18, 35, and 50 years and two years prior to interview, and categorized as normal (18.5-25 kg/m²), overweight (25-29.9 kg/m²), obese class I (30-34.9 kg/m²), and obese class II/III (35+ kg/m²). All analyses were stratified by sex. Unconditional logistic regression was used to calculate odds ratios and 95% confidence intervals. Results: We included 420 AML cases, 265 MDS cases and 1388 controls. Obesity two years prior to diagnosis was associated with AML in both males and females (OR = 2.22, 95% CI 1.28, 3.85 and OR = 1.85, 95% CI 1.08, 3.15 for BMI ≥ 35 vs. BMI 18.5-24.9, respectively). In contrast, associations between obesity and MDS were observed only in females. Weight change in adulthood was not consistently associated with either outcome. Conclusion: Our results extend the emerging literature suggesting that obesity is a risk factor for hematologic malignancy and provide evidence that that the association remains regardless of timing of obesity. Obesity in adulthood is a modifiable risk factor for both MDS and AML.