Obese patients who undergo bariatric surgery—better known as weight loss surgery—may reduce their likelihood of developing skin cancer, a new study has suggested.

, led by researchers from the University of Gothenburg in Sweden and published last week in JAMA Dermatology, found that obese patients who underwent procedures like gastric bypass or gastric band surgery to help them lose weight were less likely to develop skin cancer, including melanoma.

The research used data derived from observations of 4,047 obese adults who belonged to a study cohort known as the Swedish Obese Subjects. 2,007 patients underwent bariatric study, while 2040 did not have surgery but “received the customary treatment for obesity” from their doctors.

Researchers found that the surgery patients were significantly less likely to have developed skin cancer during the period between their enrollment in the study and the follow-up, an 18 year window on average.

This phenomenon did not appear to be influenced by how obese subjects were compared to other members of the cohort, nor was it influenced by how much they drank or if they smoked. If they had had surgery at all, their likelihood of skin cancer was reduced.

The study’s subjects were mostly (71 percent) female, with an average age of 48 years old.

There are several types of gastric surgery, but the U.S. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), two of the most common in the United States—and the ones which some of this study’s Swedish subjects underwent—are gastric bypass and banding.

In gastric bypass, a surgeon staples part of a patient’s stomach to form a small pouch in the upper part of the organ. The surgeon then attaches the patient’s small intestine to the pouch, allowing food to “bypass” most of the stomach. As a result, the patient’s stomach has less room for food and becomes full sooner leading the patient to eat less.

“The bypass also changes gut hormones, gut bacteria, and other factors that may affect appetite and metabolism,” according to NIDDK.

Surgery involving a gastric band works similarly, but involves a surgeon inserting “a ring with an inner inflatable band” around a person’s stomach to achieve the effect of making the stomach smaller. This was the variant of the surgery most of the Swedish test subjects received.

A third type of surgery patients in the Swedish study received, vertical banded gastroplasty, uses both a staple and a band to make the stomach smaller, according to .

More research into the relationship between weight loss, weight loss surgery and skin cancer will be necessary to show causality and to verify whether the findings are replicable, as the cohort used for the Swedish study was not necessarily representative of a larger population.