Early inpatient radiation for central nervous system (CNS) tumors: Timing, predictors, and in-hospital outcomes.

e14036 Background: Initiating radiation therapy (RT) early during acute CNS tumor admissions may mitigate complications. We examined whether RT within 48 hours of admission is associated with different in-hospital outcomes than later RT, and explored patient and hospital factors linked to early RT. Methods: Using the Nationwide Inpatient Sample (2016–2020), we identified 332,100 CNS tumor hospitalizations and classified encounters by RT timing: ≤48 hours (n=3,495; 1.1%) versus >48 hours (n=328,605; 98.9%). Categorical outcomes were compared with Pearson chi square tests; continuous measures with t-tests. A multivariable logistic regression modeled predictors of receiving early RT, reporting adjusted odds ratios (OR) with 95% confidence intervals (CI). Results: Compared with the later group, early RT was associated with lower in-hospital mortality (1.7% vs 3.5%, p<0.001), lower need for mechanical ventilation (1.4% vs 5.3%, p<0.001) vasopressors (0.3% vs 0.8%, p=0.001), and lower rates of acute kidney injury (4.7% vs 6.3%, p<0.001), sepsis (2.3% vs 5.4%, p<0.001), hemorrhage (6.0% vs 9.3%, p<0.001), organ failure (15.0% vs 23.9%, p<0.001), and major adverse cardiac events (4.3% vs 7.3%, p<0.001). Palliative care consultation (5.2% vs 11.1%, p<0.001) and DNR orders (8.6% vs 13.5%, p<0.001) were less common with early RT. Seizures (20.7% vs 24.4%, p<0.001) and acute hydrocephalus (3.4% vs 5.2%, p<0.001) were less common with early RT. Patients receiving early RT were younger (49.81±23.10 vs 50.63±23.68 years, p=0.041), had similar comorbidity burden (Charlson Comorbidity Index 4.801±2.645 vs 4.790±2.578, p=0.796), longer length of stay (7.37±13.32 vs 6.84±9.39 days, p=0.018), and higher total charges ($143,869±281,692 vs $100,646±143,754, p<0.001). In multivariable modeling of predictors of receiving early RT, early RT had lower odds of ventilation (OR 0.287, 0.203–0.406, p<0.001), vasopressor use (OR 0.387, 0.209–0.719, p=0.003), sepsis (OR 0.455, 0.349–0.594, p<0.001), hemorrhage (OR 0.722, 0.613–0.850, p<0.001), organ failure (OR 0.663, 0.569–0.772, p<0.001), MACE (OR 0.746, 0.611–0.911, p=0.004), acute hydrocephalus (OR 0.565, 0.456–0.699, p<0.001), seizures (OR 0.843, 0.754–0.944, p=0.004), and brain surgery (OR 0.812, 0.740–0.891, p<0.001). In contrast, frailty/malnutrition/sarcopenia emerged as a significant positive predictor of early RT (OR 1.306, 1.156–1.477, p<0.001), indicating that patients flagged as frail were more likely to receive radiation within the first 48 hours despite overall markers of acuity tending to delay treatment. Conclusions: Early RT patients experienced significantly lower mortality and markedly reduced rates of critical complications. These findings indicate that delivering RT within 48 hours confers a substantial protective effect and supports efforts to expedite radiation initiation for hospitalized CNS tumor patients.