Measuring abdominal fat (obesity), including waist circumference, is a better predictor of the risk of developing hematological malignancies, especially multiple myeloma, than body mass index (BMI), according to a population-based study in Sweden.
The study, “Body composition measurements and risk of hematological malignancies: A population-based cohort study during 20 years of follow-up,” appeared in the journal PLOS ONE.
Despite an increased knowledge of why people develop these diseases, limited information is available on modifiable risk factors. However, like other cancer types, being overweight and obese has been implicated as a risk factor for these cancers.
Most of the evidence about the link between high BMI and blood cancers comes from self-reported data, which is known to be susceptible to misclassification.
BMI may also lead to incorrectly classifying people with high muscular mass as overweight or obese.
Abdominal fat has also been found to be a better risk factor than BMI for the development of cardiovascular and liver disease, as well as for dementia.
Based on this, the team from Sweden hypothesized that abdominal fat may be a better predictor than BMI for the development of blood conditions. To address this, they used a population-based study — the EPIC cohort study, part of the Malmö Diet and Cancer study — to explore which body composition measurements best predict development of blood diseases, focusing on lymphoma, leukemia and myeloma.
In the EPIC study, body measurements were documented by healthcare professionals rather than being self-reported by the study participants. It invited all adult inhabitants of Malmö, Sweden, in predefined age ranges, to undergo a baseline examination and measurements of body composition and fill out a self-administered questionnaire from March 1991 to September 1996.
Body measurements included height, weight, BMI, waist circumference (WC), hip circumference, waist-hip ratio (WHR), waist-to-height ratio (WHtR), waist-to-hip-to-height ratio (WHHR, the WHR divided by height), body composition, body fat percent (BFP), and A Body Shape Index (ABSI), which takes into account WC, height, and BMI.
The final group of 27,557 participants included 16,750 women (60.8%) and 10,807 men (39.2%). Their mean age was 58.1 and BMI was 25.7 kg/m2, with 46.7% of women and 62.4% of men being overweight (BMI value of 25 or higher). About one-third (28.2%) were current smokers.
Median follow-up time was 19.8 years. A total of 564 people (2.1%) developed a blood condition, including 300 women (1.8%) and 264 men (2.4%), a significant gender difference.
There were 107 cases of myeloma, 299 of non-Hodgkin’s lymphoma (NHL), eight of acute lymphatic leukemia, 13 of Hodgkin’s lymphoma, and 129 cases of myeloid malignancies, among other subtypes. At the end of the follow-up period, 210 of 564 (37.2%) people with a blood disease were alive.
Waist circumference and A Body Shape Index were the only variables predicting development of any blood condition. Then, the results showed that the risk of developing myeloma was associated with abdominal fat (WC, WHR, and WHtR). No associations were found with myeloid malignancies and NHL.
This finding may reflect that “NHL is a heterogenous group of malignancies with different risk factors and that [body composition] measurements might be related to some but not all NHLs,” the team wrote.
Unlike previous studies, risk of myeloma was not greater in overweight individuals, as assessed with BMI. However, obese individuals (BMI higher than 30 kg/m²) had an elevated risk of developing the condition compared to those with normal weight (18.5 to 24.9 kg/m2).
“In conclusion, our study shows that measurements of [abdominal fat] better predict the risk of developing [blood diseases]” compared to BMI, the researchers wrote.
Among the study’s limitations, they mentioned not addressing potential changes in body composition measurements along the study period, and at what stage in life and the duration to which an individual needs to have excess body fat to increase their risk for a blood cancer.