Epidemiology and survival of adolescent and young adults with brain metastases compared to older adults.

PURPOSE: Despite recent survival improvements among adolescents and young adults (AYA) with cancer, those presenting with brain metastasis (BM) continue to face poor prognoses. This study aims to compare the epidemiology, tumor-specific characteristics, and overall survival (OS) of BM in AYA versus older adults. METHODS: Using the U.S. National Cancer Database, patients diagnosed with stage IV cancer and synchronous BMs from 2010 to 2019 were included. AYAs were defined as individuals 15–39 years; adults were ≥ 40 years. The prevalence and distribution of synchronous BMs were compared between AYAs and older adults using Fisher’s exact tests. OS was estimated using Kaplan-Meier models. RESULTS: Among patients with stage IV cancer, 7.0% of AYAs (n = 3,333/47,937) and 11.0% of older adults (n = 187,688/1,703,114) presented with BMs. Irrespective of patient sex, AYAs more frequently presented with BMs from lung, melanoma, and soft tissue and bone primaries and less often with BMs from colorectal and kidney primaries (all padj<0.05). Compared to older adults, male AYAs more often had BMs from testicular (OR = 1.42; 95CI = 1.16–1.76, padj=0.002) and head and neck (OR = 2.27; 95CI = 1.33–3.64, padj=0.009) primaries; and female AYAs less commonly had BMs from HR+/HER2 + breast carcinoma (OR = 0.67; 95CI = 0.52–0.85, padj=0.002). Overall, AYAs with BMs experienced improved OS compared to older adults (HR = 0.55, 95CI = 0.53–0.58, padj<0.001), particularly among breast, colorectal, head and neck, lung, melanoma, soft tissue and bone, and testicular primaries (all padj<0.05). CONCLUSIONS: AYAs presenting with BMs demonstrate distinct primary tumor distributions and longer OS compared to older adults. These findings underscore the need for tailored approaches to AYAs with BMs.