Weight loss tied to a dramatic drop in cancer risk

A large new study found that people who lost significant amounts of weight through bariatric surgery gained a striking benefit: Their likelihood of developing cancer fell sharply.

The study, published Friday in JAMA, followed more than 30,000 adults with obesity for about a decade. It found that those who underwent weight loss surgery had a 32 per cent lower risk of developing cancer and a 48 per cent lower risk of dying from the disease, compared with a similar group of people who did not have the surgery.

On average, the people who had weight loss surgery lost about 25 kilograms more than those who did not over the course of the study. The researchers found that the more weight people lost, the more their cancer risk fell.

Obesity is a strong driver of cancer risk. Health authorities have linked excess weight to higher rates of many cancers. The new study is among the largest and most rigorous to suggest that the increased risk can be reversed in people who lose substantial amounts of weight.

While the new research focused on weight loss through bariatric surgery, the authors of the study speculated that the benefit would apply to weight loss through other methods as well, such as diet and exercise or the use of weight loss medications. Dr Steven E. Nissen, a co-author of the study, said the findings “provide one more reason why people who are obese should lose weight”.

“It’s an important public health message,” said Nissen, the chief academic officer of the Heart, Vascular and Thoracic Institute at the Cleveland Clinic. “I think a lot of the public doesn’t understand or realise that obesity is such a strong risk factor for cancer, and they certainly don’t understand that it’s reversible.”

One expert who was not involved in the study, Dr Ania Jastreboff, said that it demonstrates that treating obesity and achieving “clinically meaningful” weight reductions can improve health outcomes for patients. “That’s a really important finding,” said Jastreboff, an associate professor at the Yale School of Medicine and the director of weight management and obesity prevention at the Yale Stress Center.

“I think a lot of the public doesn’t understand or realise that obesity is such a strong risk factor for cancer, and they certainly don’t understand that it’s reversible.”

Steve E. Nissen of the Heart, Vascular and Thoracic Institute

According to the Centers for Disease Control and Prevention, obesity is a leading cause of preventable cancers, along with smoking, heavy drinking and exposure to ultraviolet radiation. People who are overweight or obese have a higher risk of developing 13 different types of cancer, including endometrial, breast, kidney, liver, esophageal and colorectal. The CDC estimates that the 13 types of cancer linked to obesity make up 40 per cent of all cancers diagnosed in the United States each year.