Association between UV irradiation exposure by geographic region and stage at presentation in patients with melanoma

Summary: Abstract Body: This retrospective cohort study investigated the association between UV irradiation exposure by geographic region of the United States and melanoma stage at diagnosis. We used the National Cancer Database (NCDB) to identify 644,489 patients with primary cutaneous melanoma from 2004 to 2022. Geographic regions were determined by NCDB facility region at diagnosis. Chi-square and Mann-Whitney U tests were used to assess differences by region in sociodemographic variables, comorbidities, body site of the melanoma, and histologic subtype; multivariable ordinal logistic regression was used to assess odds of higher clinical T-stage at diagnosis (categorized as melanoma in situ, cT1-cT2, and cT3-cT4), adjusting for the aforementioned variables. Linear regression was used to model the association between regional UV exposure and odds of higher stage at presentation. Significant regional differences were observed in UV irradiation (ranging from 3,013 J/m2 in New England (NE) to 4,468 J/m2 in the Mountain region, p<.001), histologic subtype (67% superficial spreading in the Mountain region to 80% in NE and Pacific regions, p<.001), and stage at diagnosis (12% cT3-cT4 in NE to 19% in the E. South Central region, p<.001). Relative to New England, the E. South Central region had the highest adjusted odds of presenting with more advanced melanoma (aOR 1.68, p<.001), while the Pacific region had the lowest (aOR 1.13, p<.001). Each 1,000 J/m2 increase in UV irradiation was associated with 22.6% higher odds of more advanced stage (p<.001), although the odds of increased stage at diagnosis were higher than expected for the E. South Central region (p=.030). These findings reveal that regions with increased UV exposure have a higher likelihood of advanced melanoma at presentation, highlighting the need for increased awareness and targeted screening and prevention strategies in high-UV areas. Gracia M. Vargas¹, Mohammad S. Farooq¹, Neha Shafique¹, Michael E. Ming², John T. Miura¹, Giorgos C. Karakousis¹ 1. Surgery, Penn Medicine, Philadelphia, PA, United States. 2. Dermatology, Penn Medicine, Philadelphia, PA, United States. Pigmentation, Melanoma, and Melanoma Immune Surveillance