Who gets access? National discrepancies in clinical trial enrollment among patients with brain metastases.

1655 Background: Patients with brain metastases (BM) have historically been underrepresented in clinical trials. Contemporary national data describing clinical trial enrollment (CTE) patterns and sociodemographic predictors in this population remain limited. Methods: Using the National Cancer Database, adults (≥18 years) diagnosed with BM (2010-2021) from the five most common primary sites (lung, breast, melanoma, colorectal, and renal cell carcinoma) were included. The key outcome was CTE (yes/no). Multivariable logistic regression was used to evaluate associations between enrollment and primary tumor site, age, sex, race/ethnicity, facility type, geographic region, residence, insurance status, area-level education and income, comorbidity burden (Charlson-Deyo score), and time epoch (2010-2013, 2014-2017, 2018-2021). Results: The analytic cohort included 238,129 patients with BM (lung n=206,813; melanoma n=10,394; breast n=9,915; renal n=7,409; colorectal n=3,598). Overall, <1% of patients (n=385) had CTE. In adjusted analyses, compared with patients aged 18-39 years, those aged 40-64 years (aOR: 0.15) and ≥65 years (aOR: 0.12) had significantly lower odds of enrollment (P<0.001). Female sex was associated with higher enrollment (aOR: 1.30, P=0.013), while Hispanic ethnicity was associated with lower enrollment compared with non-Hispanic White patients (aOR: 0.39, P=0.014). Higher comorbidity burden (Charlson–Deyo score: 2-3) was associated with lower enrollment (aOR: 0.68, P=0.04). Treatment at an academic/research facility had the highest odds of CTE compared with community facilities (aOR: 4.83, P<0.001), as well as care within an integrated network (aOR: 1.87, P=0.001). CTE increased over time (2014-2017, aOR 1.58, P=0.002; 2018-2021, aOR 1.63, P=0.001, vs 2010-2013). Conclusions: CTE among patients with BM was low across primary tumor sites. Enrollment was higher at academic facilities and among younger patients, while Hispanic patients had lower odds of enrollment. These findings indicate persistent disparities in clinical trial access and support more inclusive enrollment strategies for patients with BM. Key predictors of CTE. Variable Strata aOR (95% CI) P Sex Male (Ref) - - Female 1.30 (1.06–1.60) 0.013* Race/ethnicity NH-White (Ref) - - NH-Black 0.83 (0.57–1.16) 0.292 Hispanic 0.39 (0.16–0.77) 0.014* Asian/Other 0.87 (0.54–1.32) 0.526 Facility type Community (Ref) - - Academic/Research 4.83 (3.69–6.39) <0.001* Integrated Network 1.87 (1.31–2.67) 0.001* *Geographic region, residence, and insurance status were insignificant.