EPID-29. EPIDEMIOLOGICAL CHARACTERIZATION OF BRAIN METASTASES IN MELANOMA: A LARGE POPULATION BASED-STUDY FROM 2014-2024

Abstract Brain metastases (BM) are the second most common cause of mortality in metastatic melanoma. Despite increased screening, mortality remains substantial. Additionally, population-based studies of melanoma BM capture only synchronous metastases, therefore up-to-date epidemiological and survival studies may better inform screening and management strategies. Thus, we retrospectively analyzed the TrinetX Oncology dataset to study the prevalence and survival patterns of patients with melanoma BM. Data from 13,505 patients with histologically-confirmed melanoma was extracted. Demographic and clinical parameters were compared between patients with and without BM via t-test and chi-squared analysis. Overall survival (OS) was evaluated using Kaplan-Meier and Cox regression analyses after cohorts were propensity-matched for age, sex, race, ethnicity, stage, extracranial metastases, excision of skin lesions, radiation, and antineoplastic utilization. In our study, the prevalence of BM was 7.3% (9.2% precocious, 22.5% synchronous, 68.3% metachronous). Compared to patients without BM, patients who developed BM were more often male (p<0.0001), non-Hispanic (p<0.0001), White (p<0.02), and presented with advanced-stage disease (p<0.0001). Patients with unspecified malignant melanoma (p<0.0001) and nodular melanoma (p<0.0001) were more likely to develop BM compared to those with other histological subtypes. Additionally, patients with BM were more likely to have ulceration (p<0.0001) and extracranial metastases (p<0.0001). Skin excision procedures were less common in patients with BM (p<0.0001), whereas radiotherapy and antineoplastics were more common. When assessed from melanoma diagnosis, patients who developed BM any time along their disease course had reduced OS (HR(95% CI): 2.265(1.934-2.653)). When assessed from metastatic onset, patients with BM had reduced OS compared to those with only extracranial metastases (HR (95% CI): 2.197(1.883-2.563)). Synchronous BM were associated with decreased OS compared to metachronous BM when assessed from melanoma onset (HR(95% CI): 0.6(0.442-0.815)), but there was no survival difference after BM development. In conclusion, BMs decrease OS in melanoma. Our findings may inform screening and management of patients at risk for melanoma BM.