Weight-loss surgery can significantly reduce the risk of many cancers

By Dennis Thompson
health day reporter

WEDNESDAY, June 8, 2022 (HealthDay News) — Losing weight through weight-loss surgery can significantly lower your risk of developing or dying from cancer, three new studies show.

Obese people who have suffered bariatric surgery were at least half as likely to develop certain types of cancer and more than three times less likely to die of cancer than heavy people who did not have the procedure, according to a study presented Tuesday at the American Society for Metabolic and Bariatric Surgery’s (ASMBS) annual meeting, in Dallas.

Another much larger study conducted by the Cleveland Clinic found similar, albeit smaller, benefits from weight loss surgery – a 32% risk of developing cancer and a 48% risk of cancer-related death, according to the results published on June 3 in the Journal of the American Medical Association.

People must lose at least 20% of their weight to achieve this protection against cancer, a goal that is far beyond the reach of people trying to lose weight through diet and exercise, said lead researcher Dr. Ali Aminian, director of Bariatric and Cleveland Clinic Metabolic Institute.

“Most patients with a lifestyle change cannot meet this threshold,” Aminian said. “I think this study suggests that instead of just focusing on lifestyle modification to reduce cancer risk, we need to use effective treatments to obesity.”

The results of the new studies make sense, said ASMBS President Dr. Shanu Kothari.

“We know that people who have weight loss surgery live longer than people who qualify for surgery but don’t,” Kothari said. “The main reason is that they have less heart attacks, but now we see that they also have less cancer. That’s why they live longer.”

Obesity linked to 13 cancers

More than 42% of Americans are obese, according to the US Centers for Disease Control and Prevention. Their excess weight increases the risk of developing 13 types of cancer that account for two out of five cancers diagnosed each year in the United States.

In fact, obesity is expected to soon exceed smoking as the leading global risk factor for developing cancer, given the global obesity epidemic, Aminian said.

For the first study, a team of Wisconsin researchers compared more than 2,100 bariatric surgery patients to more than 5,500 obese people who qualified for the procedure but did not get it, according to a report from the ASMBS meeting.

Bariatric surgery has significantly reduced the incidence of breast cancer (1.4% vs 2.7%), gynecological cancer (0.4% vs 2.6%), kidney cancer (0.10% versus 0.80%), brain cancer (0.20% vs. 0.90%), lung cancer (0.20% vs. 0.60%) and thyroid cancer (0.10% vs. 0.70%), the researchers found.

Over a decade of follow-up, the bariatric surgery group also had a much lower incidence of any new cancer (about 5.2% versus just over 12%) and a higher survival rate (93% versus 79%).

“We knew bariatric surgery would reduce cancer risk based on previous studies, but what surprised us was the magnitude of this reduction in some cancers,” said researcher Dr Jared Miller, surgeon general and bariatric at Gundersen Lutheran Health System in La Crosse, Wis.

The Cleveland Clinic study involved even more patients, with more than 5,000 having undergone weight loss surgery versus more than 25,000 who did not, according to the Journal of the American Medical Association report.

After 10 years, 3% of patients in the bariatric surgery group and 5% in the non-surgical group developed obesity-related cancer, the researchers found. About 0.8% of operated patients and 1.4% of non-operated people died of cancer.

The analysis showed that weight loss has a dose-dependent relationship with cancer risk — the more weight you lose, the lower your cancer risk, Aminian said.

Another study presented at the ASMBS meeting on Tuesday also found that bariatric surgery reduced the risk of Colon Cancer by 37%.

This study combined data from 13 previous weight-loss surgery studies that followed more than 3.2 million patients for 10 years, said researcher Dr. Michal Janik, general and bariatric surgeon at the Military Institution of Aviation Medicine in Warsaw, Poland. .

Previous studies have suggested that bariatric surgery may increase the risk of Colon Cancerbut this large-scale analysis found the opposite to be true, Janik said.

“We found something that was contrary to these earlier studies, because we did a very detailed analysis of all the studies,” Janik said.

Bariatric surgery is currently the only way to achieve the kind of weight loss needed to prevent cancer, Aminian and colleagues say.

Clinical trials have shown that intensive dieting and exercise can lead to an average weight loss of almost 9% in one year, they said in briefing notes.

Books should stay away

The researchers agreed that weight must remain stable for cancer protection to remain stable and argued that at this stage bariatric surgery provides the most lasting benefits.

However, Aminian noted that new drugs in development could soon help people lose enough weight to provide similar protection against cancer.

“There are new drugs in the pipeline that can help patients achieve that 20-25% weight loss,” Aminian said. “And if these drugs become available to patients and available to the public, then we should see the same results.”

Fat cells promote many risk factors for different types of cancer, Miller said, including systemic inflammation and high levels of the hormones insulin and estrogen.

“We believe weight loss bariatric surgery indirectly affects all of these different mechanisms, thereby decreasing cancer incidence and reducing cancer risk,” Miller said.

Results presented at medical meetings are considered preliminary until published in a peer-reviewed journal.

More information

The US National Cancer Institute has more on obesity and cancer.

SOURCES: Ali Aminian, MD, director, Cleveland Clinic Bariatric and Metabolic Institute, Cleveland, Ohio; Shanu Kothari, MD, president, American Society for Metabolic and Bariatric Surgery; Jared Miller, MD, general and bariatric surgeon, Gundersen Lutheran Health System, La Crosse, Wisconsin; Michal Janik, MD, general and bariatric surgeon, Military Institute of Aviation Medicine, Warsaw, Poland; Journal of the American Medical Association, June 3, 2022

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