The Effects of Sun Exposure and Pigmentation Phenotype on Prognosis in Metastatic Melanoma

Ultraviolet radiation exposure and a fair pigmentation phenotype are well-established risk factors for primary cutaneous melanoma. However, the prognostic relevance of these risk factors is largely unexplored in metastatic disease. The aim of this study was to examine whether phenotypic characteristics and sun exposure patterns affect the prognosis of metastatic melanoma with immunotherapy available. In this retrospective study, 210 patients with stage IV melanoma were included. All patients were asked to answer a standardized questionnaire regarding risk factors for melanoma, including items on sun exposure habits and self-assessment of phenotypic features. Survival analyses were performed with overall survival as the endpoint. Patients who reported >5 severe sunburns during childhood had a significantly decreased risk of death compared to patients with 0-1 sunburn (HR 0.46, CI 0.25-0.85, p=0.013). A fair or intermediate pigmentation phenotype was associated with a decreased risk of death compared to a dark phenotype after adjustment for distant metastasis category (HR 0.57, CI 0.34-0.93, p=0.026). This study indicates that the number of severe sunburns during childhood is associated with a more favourable prognosis in metastatic melanoma. However, due to the limited size of the study population, further research is required to confirm these results.