• New research finds that bariatric surgery can provide additional health benefits besides weight loss for people living with obesity.
  • The risk of developing 6 types of cancer associated with obesity is significantly lowered for those who undergo surgery when compared to their peers.
  • Their risk of developing any type of cancer is also greatly reduced when compared to those living with obesity who do not undergo weight-loss surgery.

For many years, bariatric surgery has been a successful way to help people living with obesity shed unhealthy weight.

New research suggests that it may also help to reduce the risk of developing six types of cancer known to be associated with obesity.

Additionally, the new study’s findings, which were presented at the 2022 annual meeting of the American Society for Metabolic and Bariatric Surgery (ASMBS), suggest that people who underwent weight-loss surgery had a significantly lower risk of developing any type of cancer compared to their peers living with obesity who had not had surgery.

For this study, researchers looked at more than 1,600 people living with obesity who had either gastric bypass surgery (where the stomach is divided to reduce its size) or sleeve gastrectomy surgery (where a portion of the stomach is removed).

They were compared against a control group of over, 2,100 individuals with obesity who did not undergo surgery and were matched according to sex, age, and BMI.

They found that those who underwent bariatric surgery were far less likely to develop breast cancer during a 10-year study period (1.4 percent) than those who did not have surgery (2.7 percent).

Similar risk reductions were seen for gynecologic cancer (0.4 percent versus 2.6 percent), kidney cancer (0.10 percent versus 0.80 percent), brain cancer (0.20 percent versus 0.90 percent), lung cancer (0.20 percent versus 0.60 percent), and thyroid cancer (0.10 percent versus 0.70 percent).

Only 5.2 percent of those who had bariatric surgery developed some type of cancer during the study period, compared to 12.2 percent of those in the non-surgical control group.

The overall 10-year survival rate for those who had surgery was 92.9 percent, while just 78.9 percent of the non-surgical group survived past 10 years.

“Patients live longer after bariatric surgery because they have less cardiac events and less cancers,” Dr. Shanu Kothari, president of the ASMBS, told Healthline.

Study-co-author Dr. Jared R. Miller, a general and bariatric surgeon at Gundersen Lutheran Health System, said that bariatric surgery offered a surprisingly high level of protection against certain types of cancer.

“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,” said Miller.

An unrelated studyTrusted Source involving more than 30,000 patients with obesity, published in JAMA, had similar findings.

Researchers at the Cleveland Clinic found that both obesity-related cancer and cancer-related mortality were significantly reduced among patients who had bariatric surgery compared to those who did not.

Link between obesity and cancer is clear — but not clearly understood

Kothari said that obesity is a major risk factor for 13 types of cancer.

The chronic inflammatory state caused by excessive body weight “somehow triggers a cellular change to cancerous cells,” he said. “Following weight loss, the inflammatory process is reduced and decreases the likelihood of cellular transformation to cancerous cells.”

The link between excessive body weight and cancer is still not fully understood, however, Kothari told Healthline.

In addition to reduced inflammation, weight loss can cause reductions in estrogen levels (a known risk factor for breast cancer, in particular) and beneficial changes in epigenetics and the gut microbiome, he said.

“Obesity is also associated with physical inactivity and ingestion of foods with high caloric intake — both associated with an increased risk of cancer,” Dr. Anton Bilchik, Ph.D., a surgical oncologist and chief of medicine at Providence Saint John’s Health Center in Santa Monica, Calif., told Healthline.

He also noted that weight loss is associated with improved nutrition, eating less processed food, more exercise, and lower calories — all of which may also factor into reducing the risk of cancer.

Miller said the significant and long-term weight loss most patients experience through bariatric surgery likely plays a critical role in cutting their cancer risk.

“If you drop a few pounds and then gain it back in a few months, you’re probably not going to see a cancer reduction,” he said.

People who lose and keep off weight comparable to bariatric surgery patients through diet and exercise likely would also reduce their cancer risk.

“Weight loss is weight loss,” said Bilchick. “There is nothing particular about bariatric surgery other than most patients selected for this procedure have failed non-surgical weight loss approaches.”

However, Miller said it’s rare for obese people to lose the 60-70 percent of excess body weight typically seen with bariatric surgery through diet and exercise alone.

“There’s probably a few champion stories, but the vast majority of people are not going to be able to lose equivalent weight and keep it off long enough to experience benefits,” said Miller.

Weight-loss surgery is generally offered only to people with severe obesity — typically those who are 75 to 100 pounds overweight or have a BMI of 35 or higher with an obesity-related disease such as diabetes or high blood pressure.

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