Site-specific analysis of treatment modalities and survival in brain metastases from neuroendocrine neoplasms: A real-world analysis.

e14006 Background: Brain metastases (BM) from neuroendocrine neoplasms (NENs) are rare and associated with poor prognosis. Limited data exists in the literature regarding the impact of different treatment (Tx) modalities on survival outcomes in NENs with BM, particularly in relation to primary tumor sites. Methods: NCDB data (2010–2021) was analyzed to assess Tx modalities and their association with primary tumor sites, focusing on NEN histological subtypes including small cell cancer (SCC). Kaplan-Meier analysis estimated median overall survival (OS) in months (mo). Multivariate analyses evaluated the impact of primary sites and Tx combinations, including systemic therapy (Sys) with stereotactic radiosurgery (SRS), whole-brain radiotherapy (WBRT), and standalone therapies. Results: A total of 42,291 patients were included with a median age of 66 years (IQR: 59–72), 50.5% were males, and 87.8% white. OS was highest with Sys+SRS (OS: 10.3 mo) and Sys+WBRT (OS: 8.7 mo); Sys-only Tx showed OS of 7.8 mo, while SRS-only (OS: 2.9 mo) and WBRT-only (OS: 2 mo) had poorer outcomes (P < 0.0001). Compared to Sys+SRS, multivariate analysis showed increased risk of death for Sys+WBRT (HR = 1.22, P < 0.001), Sys only (HR = 1.33, P < 0.001), SRS only (HR = 2.19, P < 0.001), and WBRT only (HR = 3.13, P < 0.001). Breast cancer had similar OS compared to lung primaries (HR = 1.15, 95% CI: 0.77-1.71, P = 0.500). Gastrointestinal cancers (large intestine/rectum and small intestine) showed no differences in OS (HR = 1.02, 95% CI: 0.92-1.14, P = 0.667). Genitourinary cancers, comprising male and female sites, had a modestly higher but non-significant HR (HR = 1.13, 95% CI: 0.97-1.31, P = 0.123). Other systems, including the endocrine system, oral cavity/pharynx, and soft tissues, showed no difference (HR = 1.00, P = 0.948). Conclusions: Sys+SRS was associated with the best OS in NEN-BM, whereas single modality approaches alone had significantly worse outcomes. After adjusting for confounders, primary tumor site did not emerge as a significant determinant of survival. Primary sites and Tx modalities. Primary Site All, N (%) Sys + SRS, n (%) Sys + WBRT, n (%) Sys only, n (%) SRS only, n (%) WBRT only, n (%) Breast & Endocrine System 39 (0.2) 6 (0.2) 11 (0.2) 8 (0.1) 0 (0.0) 4 (0.1) Esophagus and Stomach 110 (0.4) 11 (0.6) 22 (0.3) 38 (0.5) 3 (0.8) 12 (0.5) Female Genitourinary System 105 (0.4) 9 (0.5) 29 (0.3) 30 (0.4) 1 (0.3) 11 (0.5) Large Intestine and Rectum 132 (0.5) 9 (0.5) 26 (0.3) 52 (0.7) 4 (1.1) 6 (0.3) Liver, Biliary System & Pancreas 158 (0.7) 12 (0.7) 41 (0.4) 43 (0.6) 0 (0.0) 18 (0.8) Male Genitourinary System 87 (0.4) 7 (0.4) 21 (0.2) 32 (0.4) 3 (0.8) 7 (0.3) Lung 24103 (97.1) 1713 (96.6) 8516 (98.1) 7313 (96.9) 354 (96.2) 2144 (97.2) Small Intestine 10 (0.0) 0 (0.0) 2 (0.0) 3 (0.0) 1 (0.3) 1 (0.0) Soft Tissues, Oral Cavity & Pharynx 70 (0.2) 6 (0.3) 12 (0.1) 27 (0.3) 3 (0.5) 6 (0.1)