Background

Melanoma of the skin is currently the 19th most common cancer globally. Nearly 290,000 new cases and 61,000 deaths were reported in 2018 and world-wide incidence rates continuously rise with annual increases as high as 4–6% in high-risk fair-skinned populations [Citation 1]. Sweden has an age-standardized incidence rate of 24.7 per 100,000, compared to 3.5 per 100,000 globally, and thereby the sixth highest incidence in the world. National Swedish data shows a worrying trend where the number of very thick melanomas (Breslow thickness> 4 mm), the group with the least favorable diagnosis, have more than quadrupled in the last two decades [Citation 2]. Advanced melanoma is an aggressive and highly metastatic disease. Its metastatic pattern is notoriously unpredictable, manifesting as multifocally dispersed disease involving practically any organ of the body in some patients, and as persistently reoccurring indolent locoregional disease in others. Any genetic characteristics underlying these differences remain largely unknown [Citation 3–5].