Clinical outcomes and prognostic factors of Ommaya reservoir-based intrathecal chemotherapy in lung cancer leptomeningeal metastasis: a retrospective cohort study.

OBJECTIVES

To evaluate clinical outcomes and identify prognostic determinants in patients with lung cancer leptomeningeal metastasis (LCLM) treated with Ommaya reservoir-based intrathecal (IT) chemotherapy.

METHOD: We retrospectively reviewed 154 LCLM patients treated at Fudan University Shanghai Cancer Center (2022-2025). All patients underwent Ommaya reservoir implantation, or combined with VP shunt. IT pemetrexed (30 mg/week) was delivered for 4-6 consecutive weeks. Clinical characteristics, cerebrospinal fluid (CSF) and magnetic resonance imaging (MRI) features were collected. Survival outcomes were assessed using Kaplan-Meier and Cox regression analyses.

RESULTS

The cohort had a median age of 59 years (IQR, 53-65) with predominance of female sex (59.1%), lung adenocarcinoma (98.1%), and EGFR mutations (76.7%). Median overall survival (OS) for the entire cohort was 331 days (IQR, 266-446). To provide guidance on clinical decision making, we established an exploratory four-tier prognostic system integrating KPS and intracranial pressure (ICP), categorizing patients into distinct prognostic quartiles. Our analysis revealed that among patients with Karnofsky Performance Status (KPS) ≥70, a normal ICP was associated with superior survival. Conversely, in patients with KPS ≤ 50, a decrease in intracranial pressure indicates a poorer prognosis for the patients. Multivariate Cox regression identified KPS, extracranial metastasis, MRI morphology, and CSF glucose/protein as independent prognostic factors. A nomogram developed from these variables showed excellent discrimination (AUC = 0.894) and robust calibration.

CONCLUSIONS

This study establishes a practical risk stratification system and a prognostic nomogram to assist individualized clinical decision-making for LCLM patients.