Bariatric surgery is associated with a reduced incidence of skin cancers including melanoma, a large Swedish study has found.
The findings strengthen evidence that obesity is a risk factor for various cancer types and that significant weight loss can modify that risk.
The ongoing Swedish Obese Subjects (SOS) study matched more than 2,000 obese patients who chose bariatric surgery with a similar number of participants who chose conventional obesity treatment such as lifestyle modification.
The participants were mostly female (71%) and with a mean BMI greater than 40.
The mean weight loss in the surgical group was 28.7 kg at two years, 21.1 kg at 10 years and 21.6 kg at 15 years compared to ≤3 kg in the control group.
During a median follow-up time of 18.1 years, 11 SCCs and 12 melanomas occurred in the surgery group compared to 16 SCCs and 29 melanomas in the control group.
The study found that bariatric surgery was associated with a markedly reduced risk of melanoma (adjusted subhazard ratio, 0.43; 95%CI, 0.21-0.87; P = .02) and risk of skin cancer in general (adjusted subhazard ratio, 0.59; 95%CI, 0.35-0.99; P = .047).
“These findings suggest that bariatric surgery is associated with reduced incidence of skin cancer (SCC and melanoma combined) and melanoma in individuals with obesity,” the researchers said in JAMA Dermatology.
“However, bariatric surgery should not be viewed as a public health intervention specific to skin cancer.”
“Instead, these findings give additional support for an association between obesity and skin cancer and for an association between weight loss and reduced cancer incidence.”
The study found baseline BMI was not associated with the preventive effect of bariatric surgery on skin cancer incidence.
The researchers said the reduced skin cancer risk may be associated with altered metabolic or endocrine related to bariatric surgery but independent of weight loss.
“Moreover, bariatric surgery may reduce circulating cancer-associated biomarkers related to inflammation, cell proliferation, and angiogenesis.”