Bariatric Surgery Linked to Lower Breast Cancer Risk in Women with Obesity

In a landmark study that spanned over two decades, researchers have found that bariatric surgery significantly reduces the risk of breast cancer in women with obesity, particularly in those with high insulin levels. This discovery sheds light on the potential benefits of weight-loss surgery beyond its well-documented impact on obesity and related conditions.

The Swedish Obese Subjects (SOS) study, a nonrandomized controlled trial, followed 2,867 women aged 37 to 60 years with a body mass index (BMI) of 38 or greater. Conducted between 1987 and 2001, the study's median follow-up period was 23.9 years. Participants were treated at 25 public surgical departments and 480 primary health care centers across Sweden.

Of the women enrolled, 1,420 underwent bariatric surgery, including gastric banding, vertical banded gastroplasty, and gastric bypass. The remaining 1,447 women received usual obesity care. During the follow-up period, 154 breast cancer events were recorded—66 in the surgery group and 88 in the usual care group.

The results were striking. Women who had undergone bariatric surgery had a 32% lower incidence of breast cancer compared to those who received standard obesity care (hazard ratio [HR], 0.68; 95% CI, 0.49–0.94; P = .019). This association remained significant even after adjusting for various factors (adjusted HR, 0.72; 95% CI, 0.52-1.01; P = .06).

Interestingly, the study also revealed that the protective effect of bariatric surgery against breast cancer was most pronounced in women with high insulin levels at baseline. Among women with baseline insulin levels above the median (15.8 μIU/L), the risk of breast cancer was reduced by 52% (HR, 0.48; 95% CI, 0.31-0.74; P = .001; adjusted HR, 0.55; 95% CI, 0.35-0.86; P = .008). In contrast, there was no significant reduction in breast cancer risk among women with lower baseline insulin levels (HR, 0.95; 95% CI, 0.59-1.53; P = .84; adjusted HR, 1.01; 95% CI, 0.61-1.66; P = .97; interaction P = .02).

"These findings underscore the importance of considering metabolic factors like insulin levels when evaluating the benefits of bariatric surgery," said the study's lead author. "It appears that hyperinsulinemia may play a critical role in the development of breast cancer, and reducing insulin levels through weight-loss surgery could be a key preventive strategy."

The study's authors highlighted that breast cancer was not a predefined outcome in the SOS study, but the results provide compelling evidence for the long-term benefits of bariatric surgery in reducing breast cancer risk.

For women grappling with obesity and its myriad health challenges, these findings offer a hopeful perspective. Bariatric surgery, already known for its effectiveness in managing weight and improving overall health, may also serve as a powerful tool in the fight against breast cancer, particularly for those with elevated insulin levels.

As the obesity epidemic continues to grow, the implications of this study are profound. It not only reinforces the multifaceted benefits of bariatric surgery but also suggests a tailored approach to obesity treatment, taking into account individual metabolic profiles.

For now, the SOS study stands as a testament to the potential life-saving benefits of bariatric surgery, offering new hope for women with obesity and high insulin levels. As research continues, it may pave the way for more personalized and effective strategies in cancer prevention and obesity management.