A Swedish study has shown obese patients with uveal melanoma (UM) have a lower risk of developing metastases and dying from the cancer.

Led by researchers from Stockholm’s St Erik Eye Hospital, the study team assessed 581 patients diagnosed with primary UM, 20% of whom were obese (BMI≥30.0). UM-related mortality at five and 10 years after diagnosis was 9.9% and 11.3%, respectively, for patients with obesity, compared with 20.3% and 24.6% for non-obese patients. “This may be related to elevated serum leptin levels which suppress tumour leptin receptor expression, in turn reducing the activity of pathways that are associated with vasculogenic mimicry, extracellular matrix interactions and invasive behaviour,” the team wrote in their open access paper, published in the British Journal of Ophthalmology.

A similar beneficial effect of high serum leptin levels has been found in pancreatic and colorectal carcinoma, as well as in cutaneous melanoma – a phenomenon termed ‘the obesity paradox’, they said. However, type-2 diabetes and the use of insulin were associated with metastases, they noted.