Previous research revealed that being overweight or obese is a risk factor for various forms of cancer. It is also known that obese women are more likely to develop cancer than their male counterparts, and the risk level reduces with intentional weight loss. However, there is limited evidence of a relationship between obesity, weight loss, and haematological malignancy.
The latest study, published in the journal Lancet Healthy Longevity, included data from the Swedish Obese Subjects (SOS) study at the University of Gothenburg as well as data from the National Board of Health and Welfare's Cancer Registry.
The researchers analysed 2,007 people who had bariatric surgery and compared them to a control group of 2,040 obese adults who did not have surgery.
During the follow-up period, 34 individuals in the surgery group developed haematological cancer, in parallel with a significant weight loss. The corresponding number in the control group was 51 haematological cancers, with the group remaining at the level of severe obesity.
Most of the blood cancers were lymphomas, and when these were studied separately, there was a 55 per cent reduction in the risk of lymphoma in the group that had undergone bariatric surgery. The corresponding risk reduction for all blood cancers was 40 per cent.
In particular, women with high blood sugar at the start of the study seemed to benefit from bariatric surgery. This is according to Magdalena Taube, Associate Professor of Molecular and Clinical Medicine at Sahlgrenska Academy, University of Gothenburg, and corresponding author of the study.
“The benefit of the surgery is linked to baseline blood glucose levels. The reduced risk of haematological cancer was much more pronounced if the women's blood sugar levels were high at the beginning, which clearly shows that blood sugar is an important factor in cancer development,” she says.
The researchers in the study point out that the mechanisms behind the link between obesity and blood cancers are complex and involve multiple factors, such as chronic inflammation and so-called clonal hematopoiesis, a type of genetically related risk factor for blood cancer. They suggest that the metabolic improvements that take place after bariatric surgery, including reduced inflammation, may reduce the risk of cancer.
“The results provide further support of considering obesity a risk factor for haematological cancer, and that bariatric surgery can reduce the risk of blood cancer in obese women,” said Magdalena Taube, Associate Professor of Molecular and Clinical Medicine at the Sahlgrenska Academy, University of Gothenburg and corresponding author of the study.
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