Bariatric surgery is associated with a reduced incidence of hematologic cancer, specifically in women, according to a new study published in Lancet Healthy Longevity (2023;4[10]:e544-e551).
The prospective controlled Swedish Obese Subjects study was designed to compare overall mortality in 2,007 people who underwent bariatric surgery and 2,040 people who did not undergo surgery. The groups were otherwise similar in terms of age, sex, body composition, cardiovascular risk factors and psychosocial variables. Participants were recruited through campaigns in mass media and at 480 primary healthcare centers all over Sweden. The inclusion criteria were an age of 37 to 60 years and a body mass index of 34 kg/m2 or higher in men and 38 kg/m2 or higher in women before or at the time of the examination. Hematologic cancer events, including malignant lymphoma, myeloma, myeloproliferative neoplasms, as well as acute and chronic leukemias, were captured from the Swedish Cancer Registry. The main outcomes of this study were hematologic cancer incidence and mortality.
Overall, 34 participants in the surgery group, in parallel with significant weight loss, and 51 participants in the usual care control group were diagnosed with hematologic cancer during the follow-up (hazard ratio [HR], 0.60; 95% CI, 0.39-0.92; P=0.020). Moreover, there were three deaths from hematologic cancer in the surgery group and 13 deaths in the control group (HR, 0.22; 95% CI, 0.06-0.76; P=0.017). Most of the blood cancers were lymphomas, and when these were studied separately, there was a 55% reduction in the risk for lymphoma among participants who had undergone bariatric surgery (HR, 0.45; 95% CI, 0.23-0.88; P=0.020). A significant difference in treatment effect between men and women was found: Bariatric surgery was associated with a reduced incidence of hematologic cancer in women (HR, 0.44; 95% CI, 0.26-0.74; P=0.002), but not in men (HR, 1.35; 95% CI, 0.58-3·17; P=0.489; interaction P=0.031).
In particular, women with high blood sugar at the start of the study seemed to benefit from bariatric surgery, according to Magdalena Taube, PhD, an associate professor of molecular and clinical medicine at Sahlgrenska Academy, University of Gothenburg, and corresponding author for the study.
“The benefit of the surgery is linked to baseline blood glucose levels,” Dr. Taube said. “The reduced risk of hematological 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 noted that the mechanisms behind the link between obesity and blood cancers are complex and involve multiple factors, such as chronic inflammation and clonal hematopoiesis, which is a type of genetically related risk factor for blood cancer. They suggested that the metabolic improvements that occur after bariatric surgery, including reduced inflammation, may reduce the risk for cancer.
“The results provide further support of considering obesity a risk factor for hematological cancer, and that bariatric surgery can reduce the risk of blood cancer in obese women,” Dr. Taube said.
“Health-care providers and policy makers working in the field of cancer prevention should consider bariatric surgery a primary prevention resource for people with obesity,” the study authors wrote.
—Kate O’Rourke
Dr. Taube reported no relevant financial disclosures.