Obesity is a known risk factor for many cancers. A recent study, involving over 2,000 bariatric surgery patients, asks whether losing weight could reduce the risk of melanoma.

In the United States, skin cancer is the most common form of cancer.

In 2014 alone, there were almost 80,000 new cases, and by the end of 2018, it is estimated that there will be more than 90,000.

Understanding the risk factors behind every type of cancer is important in our effort to minimize the population's risk at large.

And, obesity has already been confirmed as a risk factor for a number of cancers, including endometrial, liver, kidney, colorectal, and pancreatic cancer.

The most obvious risk factor for skin cancer is unprotected sun exposure. However, according to earlier studies, obesity may also play a role.

Recently, researchers set out to further investigate obesity's role in the risk of melanoma, a quick-growing form of skin cancer.

Obesity and melanoma

Previous work has concluded that obesity increases both the risk and the growth rate of melanoma. In the recent study, however, the researchers wanted to understand whether losing weight would reduce the level of risk.

The scientists, led by Magdalena Taube, from the University of Gothenburg in Sweden, presented their findings at the European Congress on Obesity, held in Vienna, Austria.

To examine the link between obesity, weight loss, and melanoma, they took data from the Swedish Obese Subjects study—a project set up to monitor the outcomes of bariatric surgery compared against individuals using conventional obesity treatments.

Participants were more than 2,000 individuals who had undergone obesity surgery and a similar number of control participants who were matched for a range of parameters, including age, sex, body measurements, personality traits, and cardiovascular risk factors.

Their analysis demonstrated that those who had undergone surgery had a significantly lower risk of developing melanoma in the following 18 years.

A 61% risk reduction

In fact, compared with the control group, individuals in the surgery group saw a 61% drop in their risk of developing malignant melanoma, and a 42% reduced risk of all types of skin cancer.

The authors conclude, "In this long-term study, bariatric surgery reduced the risk of malignant melanoma."

"This finding supports the idea that obesity is a melanoma risk factor, and indicates that weight loss in individuals with obesity can reduce the risk of a deadly form of cancer that has increased steadily in many countries over several decades."

The link between skin cancer and obesity is somewhat surprising, and more work will be needed to uncover exactly why this is so. The findings mark yet another worrying health risk associated with obesity, but also offer a potential route to reducing the dangers.