Bariatric Surgery Can Cut Your Risk of Cancer

People with severe obesity can cut their chance of cancer, along with many other serious health problems, by a third if they have weight-loss surgery.

If you are coping with obesity and your doctor suggests weight-loss surgery, take a hard look at the science: there is growing evidence that it can cut cancer risk, address type 2 diabetes, and, overall, extend your life.

Before your doctor suggests surgery, you’ve probably already run into some of the consequences of obesity — type 2 diabetes, heart disease, sleep apnea, joint problems, migraines, as well as certain cancers. There are also emotional and practical side effects from social stigma of being obese. That’s why doctors are recommending weight-loss procedures to even teenagers.

Although you may not reach the waist size you’re dreaming of, or become entirely healthy afterward weight-loss surgery, the evidence shows you can greatly increase your health prospects.

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Cut your cancer risk

Kaiser Permanente, a large U.S. medical system, looked at data from some 90,000 patients with obesity over a decade at five hospitals. The conclusion: people with severe obesity cut their chance of cancer by a third if they had weight-loss surgery. Their risk of cancers specifically related to obesity dropped even more.

More recently, researchers at Rutgers University in New Jersey focused on people who have both severe obesity and non-alcoholic fatty liver disease (NAFLD), a problem among many overweight and obese people.

If your body looks like an apple, chances are you have fat around your liver and other organs in your abdomen. Anyone who sits much of the day, is short on sleep, and eats a standard American diet is at risk for high triglycerides, a type of lipid (or blood fat) that clogs your liver with fat. Your liver ends up looking like a marbled steak. About a quarter of all U.S. adults have fatty livers, often alongside obesity and type 2 diabetes.

Among people with obesity, some 90 percent have fatty livers; both health problems increase your cancer risk.

The Rutgers study found less dramatic numbers than Kaiser, but the researchers still make a good case for the surgery. The team looked at data from nearly 100,000 American adults with severe obesity who were newly diagnosed with NAFLD. About a third of them went on to have weight-loss surgery. This group was 18 percent less likely to develop cancer afterwards than the other patients and 25 percent less likely to develop cancers known to be related to obesity. If you have a more advanced kind of liver problem, the surgery is even more helpful.

Cancers related to obesity include colorectal, pancreatic, endometiral, and thyroid cancers, as well as hepatocellular carcinoma and multiple myeloma.

Similar benefits have shown up in other research. A 2019 study, for example, drew upon data from half a million adults with obesity who appeared on nationwide Nordic registries from 1980 through 2012. It concluded that patients who had weight-loss surgery lived longer than patients who didn’t and cut their chance of dying specifically from cancer, heart disease, and type 2 diabetes.

This isn’t a surprising result for type 2 diabetes, since most weight-loss surgery patients no longer need to take their medication or get their blood sugar under better control, at least for a while. (Losing weight may lower your A1C levels, a hallmark of type 2 diabetes and prediabetes.)

Don’t conclude, however, that everyone who has obesity in the family is destined for surgery. Exercise and careful eating do make a difference.

Walk an hour a day

When Harvard researchers looked at 32 obesity-promoting genes in more than 12,000 people, they calculated that you can cut the impact of those genes by half if you walk briskly for about an hour a day.

It’s not impossible to lose weight and keep it off, though difficult. People do succeed: The National Weight Loss Registry tracks more than 10,000 people who have maintained at least a 30-pound weight loss for a year or longer. On average, they’ve lost 66 pounds and kept it off for 5.5 years. A huge amount of them, 90 percent, exercise, on average about an hour a day — and the most frequent exercise is walking.

Your walks might help you lose belly fat, the most dangerous kind. Scientists thought that brisk walks after meals would help address metabolic syndrome, tightly linked to obesity, which includes a big waistline, high blood sugar, and high blood pressure, as well as high cholesterol or triglycerides. But a 2019 study found otherwise.

The downside of weight-loss surgery

No surgery is risk-free. Some 10 to 17 percent of patients run into complications with these procedures, and about 7 percent have a second operation. Very few die.

What can go wrong?

• Surgery may aggravate some medical conditions — blood clots, liver disease, heart disease, and kidney stones.
• If you had depression in the past, there is a chance the surgery will trigger an episode.
• The same is true of alcohol and substance abuse problems.
• Some people need more procedures to remove sagging skin. People do regain weight but rarely get back to their weight before the surgery.

Five years after maximum weight loss, patients maintain, on average, 73 percent of their maximum weight loss, according to one study. In other words, your problem isn’t gone but you’re still ahead of where you were before surgery.

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