25 September 2023

Bariatric surgery is associated with up to 40% lower risk of haematological cancer, Swedish researchers have found.

A team at the University of Gothenburg say they hope their findings, published in Lancet Healthy Longevity, could influence future research in the field.

Previous studies have shown that overweight and obesity are risk factors for several types of cancer,  and that obese women have a higher risk of cancer than their male counterparts. However, there is limited evidence of a link between obesity, weight loss and haematological cancer.

A team led by researchers from the University of Gothenburg used data from Swedish Obese Subjects (SOS) study and data from the Cancer Registry at the National Board of Health and Welfare. They included 2,007 people who underwent bariatric surgery, and compared them to a control group of 2,040 individuals, also obese, who did not undergo surgery.

During the follow-up period, 34 individuals in the surgery group developed haematological cancer, in parallel with a significant weight loss. In the control group there were 51 haematological cancers, with the group remaining severely obese.

Most of the blood cancers were lymphomas, and when these were studied separately, there was a 55% reduction in the risk of lymphoma in the group that had undergone bariatric surgery. The corresponding risk reduction for all blood cancers was 40%. After adjusting for potential confounding factors – including sex, age, alcohol intake, and smoking status – the overall risk reduction was 36%.

Women with high blood sugar at the start of the study seemed to benefit particularly from bariatric surgery, said Dr Magdalena Taube from University of Gothenburg, who co-led the study with Prof Lena Carlsson.

“The benefit of the surgery is linked to baseline blood glucose levels,” said Taube. “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.”

The researchers say the mechanisms behind the link between obesity and blood cancers are complex and involve multiple factors, such as chronic inflammation and clonal haematopoiesis. They add 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,” added Taube.


Sjöholm K, Andersson-Assarsson JC, Kristensson FM, Hjorth S, Garelius HG, Jacobson P, Svensson PA, Ahlin S, Carlsson B, Peltonen M, Carlsson LMS, Taube M. (2023) “Long-term incidence of haematological cancer after bariatric surgery or usual care in the Swedish Obese Subjects study: a prospective cohort study.” Lancet Healthy Longevity, doi: 10.1016/S2666-7568(23)00141-1.

Link: https://www.thelancet.com/journals/lanhl/article/PIIS2666-7568(23)00141-1/fulltext   

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