Weight-Loss Surgery Tied to Lower Blood Cancer Risk in Women

Bariatric surgery for obesity was associated with a reduced risk of hematologic cancers in a prospective Swedish study spanning more than three decades.

In individuals treated for obesity from 1987 to 2001, bariatric surgery was linked with a 36% lower risk of developing a hematologic cancer over subsequent decades compared with usual care (adjusted hazard ratio [aHR] 0.64, 95% CI 0.41-0.99, P=0.04), reported Magdalena Taube, PhD, of the University of Gothenburg in Sweden, and colleagues.

Of note, the association was only seen among women (HR 0.47, 95% CI 0.27-0.79), they detailed in Lancet Healthy Longevity.

"Our results suggest that obesity is a modifiable risk factor for hematological cancer and that bariatric surgery might reduce the risk of hematological cancer in women with obesity," Taube and colleagues wrote. "Healthcare providers and policy makers working in the field of cancer prevention should consider bariatric surgery a primary prevention resource for people with obesity."

The researchers also observed lower risks for lymphoma specifically (aHR 0.49, 95% CI 0.25-0.96) and death due to hematological cancer (aHR 0.29, 95% CI 0.09-0.94) associated with bariatric surgery.

In a commentary accompanying the study, Sonja Chiappetta, MD, and Vincenzo Bottino, MD, both of the Ospedale Evangelico Betania in Naples, Italy, emphasized that bariatric surgery should provide support for a change in lifestyle.

"Therefore, the role of nutrition, nutrigenomics, and fasting should also be highlighted when discussing obesity-associated cancer and cancer prevention," they wrote, adding that more biological and clinical studies looking at the role of food and calorie restriction and nutrigenomics are needed in order to "complement the global fight against the obesity epidemic and its associated diseases, especially cancer."

For their study, Taube's team looked at 4,047 adult participants (37 to 60 years) from the Swedish Obese Subjects cohort, which was designed to compare morbidity and mortality between individuals with obesity who underwent bariatric surgery (n=2,007) and a matched group of controls (n=2,040) receiving usual obesity care.

Average age of participants was about 48 years, and 71% were women. Participants were followed for up to 33 years at study cutoff (median 24.4 years in the surgery group and 22.7 years in the control group).

During follow-up, a total of 85 hematologic cancers were detected (34 in the surgery group and 51 in the usual-care group), nearly half of which were lymphomas. A total of 16 deaths from blood cancers occurred (three and 13 in the two groups, respectively).

Mean weight loss in the surgery group was 28.5 kg at the 2-year follow-up visit and sustained over time -- 20.8 kg at the 10-year follow-up visit, and 21.2 kg at the 15-year follow-up visit. In the control group, mean weight changes never exceeded a gain or loss of 3 kg.

One of the study limitations is that most patients in the surgery group underwent either vertical banded gastroplasty (68%) or banding (19%), procedures rarely used today, noted Taube and co-authors.

"However, convincing data show that the association between bariatric surgery and cancer risk depends on the magnitude of weight loss, and it should be noted that the magnitude of weight loss after vertical banded gastroplasty is similar to that after laparoscopic sleeve gastrectomy," they wrote.

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