More evidence shows weight loss surgery reduces the risk of getting cancer or dying from it, study finds

• Obesity is associated with higher risk of cancers, and weight loss surgery may help, research suggests.
• A study found weight loss surgery patients were significantly less likely to get cancer or die of it.

Weight loss surgery may cut cancer risk by at least half for people with obesity, according to research presented at the American Society for Metabolic and Bariatric Surgery Annual Meeting.

Researchers from Gundersen Lutheran Health System in Wisconsin looked at 3,776 adults with obesity, 1,620 of whom had weight loss surgery, over 10 years of follow up to compare cancer rates.

They found that weight loss surgery was associated with significantly lower risk of cancer, and cancer-related death. People with obesity were at least twice as likely to develop cancer and more than three times more likely to die from it than their peers who had weight loss surgery, researchers found.

Specifically, weight loss surgery was linked to a lower risk of breast cancer, kidney cancer, thyroid cancer, gynecologic cancer, lung cancer, and brain cancer.

While previous research has found weight loss surgery can reduce cancer risk, researchers were surprised by how significant the change was, according to Dr. Jared R. Miller, co-author of the study and bariatric surgeon at Gundersen Lutheran Health System.

"The benefits of cancer risk reduction through weight-loss surgery cannot be ignored and should be a consideration for patients with obesity and at high risk for cancer," Miller said in a press release.

Similar findings were published this week in a separate study in JAMA by researchers at the Cleveland Clinic — data from more than 30,000 people with obesity suggested weight loss surgery was linked to significantly lower cancer risk.

Surgery patients in the study lost about 55 pounds on average more than people who were advised to try losing weight through lifestyle changes, and more weight loss was linked to greater reduction in cancer risk. While weight loss, and subsequent health benefits can sometimes occur through lifestyle changes like dieting, previous research suggests that diets rarely lead to significant, long-term benefits.

Weight loss surgery is typically only recommended for people with a BMI of 35 or above, or about 75-100 pounds above what is considered a healthy weight range (although BMI is a controversial measure of health).

While the surgery is considered safe in the short-term, research suggests it does have risks, with about 20% of patients experiencing complications ranging from nutritional deficiencies, hernias, and leakages to infection, blood clots, and death.