Effect of intrathecal pemetrexed on survival in patients with lung adenocarcinoma with leptomeningeal metastasis: A propensity score matching analysis.

Abstract

e21048 Background: The effect of intrathecal chemotherapy (ITC) on the survival of leptomeningeal metastasis (LM) from lung adenocarcinoma (LUAC) has not yet been clearly defined. Methods: LUAC patients with cytologically or radiographically proven LM and receiving systemic pharmacotherapy after LM diagnosed were collected at the Fujian Cancer Hospital from July 2018 to March 2022. Patients were divided into intrathecal pemetrexed (IP) or non-IP groups and then propensity matched 1:1 into two groups. Among the matched cohort, the log-rank tests and multivariable Cox proportional hazards regression models were performed to identify predictors of survival. Median survival was calculated by using the Kaplan-Meier method. Results: A total of 165 patients with LM were included; 83 were in the IP group and 82 were in the non-IP group. After PSM, 114 patients were identified in the matched cohort. There were no statistically significant differences between IP and non-IP groups in median overall survival (13.2 months versus 10.1 months; hazard ratio 0.84, 95% CI: 0.53 - 1.33; p = 0.49). In the multivariable Cox regression analysis, only ECOG PS was confirmed as an independent prognostic factor for overall survival in the matched cohort (hazard ratio 1.83, 95% CI: 1.04 - 3.23; p = 0.037). When stratified by ECOG PS, IP improved survival in patients with poor ECOG PS (14.3 months versus 1.6 months; p = 0.002), but not in patients with good ECOG PS (12.8 months versus 12.6 months; p = 0.884). Conclusions: Our results indicated that IP may not bring survival benefit to all LUAC patients with LM, but may improve survival in patients with poor ECOG PS.