Leptomeningeal carcinomatosis in gastric cancer: a single-center retrospective analysis of 86 cases.

[BACKGROUND] Leptomeningeal carcinomatosis (LMC) is a rare but highly lethal manifestation of gastric cancer. We sought to describe its clinical features and define prognostic factors in a large single-center cohort.

[METHODS] We retrospectively reviewed 86 patients diagnosed with LMC secondary to gastric cancer at Samsung Medical Center between 2008 and 2024.

[RESULTS] The median interval from primary gastric cancer diagnosis to LMC development was 12.0 months (range, 0-106). Common presenting symptoms included headache (73.3%), nausea/vomiting (55.8%), and dizziness (48.8%). Primary gastric cancers were predominantly Borrmann type III (48.2%) or type IV (38.8%) and had an undifferentiated-type (96.5%) histology. Intrathecal (IT) methotrexate-based chemotherapy was administered to 54 patients (62.8%), with or without radiotherapy or systemic chemotherapy. Cytological response was seen in 14/54 patients (25.9%) who received IT chemotherapy. Decompressive therapies, including Ommaya reservoir, external ventricular drainage (EVD) and ventriculoperitoneal (VP) shunt were performed in 71/86 patients (82.6%). The median overall survival from LMC diagnosis was 6.0 weeks (95% confidence interval [CI]: 3.7-8.3). In multivariable analysis, age ≥ 60 years (HR 1.8) and ECOG PS > 2 (HR 2.8) were independent adverse prognostic factors. Univariable subgroup analyses demonstrated prolonged survival with intrathecal chemotherapy (HR 0.5), systemic chemotherapy (HR 0.4), and decompressive procedures (HR 0.3), whereas radiotherapy showed no significant benefit.

[CONCLUSIONS] The prognosis of gastric cancer patients with LMC remains extremely poor, and older age and poor performance status were independent adverse prognostic factors. As intrathecal chemotherapy, systemic chemotherapy, and decompressive therapies may improve survival, an individualized, multidisciplinary treatment approach is recommended.