Abstract: Background and purpose: Leptomeningeal metastasis in gastric cancer is a special form of gastric cancer metastasis to the central nervous system, which has distinct biological characteristics different from other advanced gastric cancers. This study aimed to explore the clinicopathological characteristics and prognostic survival analysis of patients with gastric cancer and leptomeningeal metastasis (GCLM). Methods: The gastric cancer database established by the Third Department of Surgery of the Fourth Hospital of Hebei Medical University from 2010 to 2019 was searched, patients with GCLM confirmed by imaging examination or cerebrospinal fluid cytology were selected, and their clinicopathological characteristics, survival prognosis and related factors of prognosis were analyzed. Results: A total of 50 GCLM patients were retrieved, accounting for 0.82% of the total gastric cancer patients. Among them, 30 cases were male (60.00%), and 20 cases were female (40.00%); the median age was 54 years (95% CI: 41-66 years), of which 22 cases (44.00%) were less than 50 years, and 28 cases were more than 50 years (56.00%); pathological types: 29 cases of poorly differentiated adenocarcinoma (58.00%), 18 cases of signet ring cell carcinoma and mucinous adenocarcinoma (36.00%), and 3 cases of mixed neuroendocrine carcinoma (6.00%). The 50 cases of GCLM patients were metachronous meningeal metastases. The median time from the diagnosis of gastric cancer to the onset of GCLM was 13.8 months (95% CI: 5.5-20.9 months), of which 23 cases had brain damage and meningeal irritation (46.00%), 18 cases had symptoms of cranial nerve function involvement (36.00%), and 19 cases had symptoms of spinal nerve function impairment (38.00%). The average number of lumbar puncture cerebrospinal fluid examinations in the whole group of patients was 3 times, of which the positive rate of cerebrospinal fluid cytology was 46.00% (23/50) after one puncture, and the positive rate after the second lumbar puncture was 76.19% (32/42). The 3rd positive rate was 77.14% (27/35). The median survival time after meningeal metastasis of the whole group was 3.8 months (95% CI: 1.30-8.60). The results of Cox multivariate analysis showed that the positive expression of the tumor marker CA19-9 in serum (HR=2.458, 95% CI: 1.189-5.080, P=0.015) and other distant organ metastases (HR=3.593, 95% CI, 1.365-9.456, P=0.010) were independent risk factors affecting the prognosis of GCLM patients, while chemotherapy after meningeal metastasis was a protective factor (HR=0.170, 95% CI: 0.049-0.591, P=0.005). Conclusion: For patients with late clinical stage of gastric cancer who have headache, nausea and vomiting, accompanied by increased intracranial pressure and meningeal irritation, one should be highly vigilant about the possibility of GCLM. Application of systemic therapy combined with local therapy can help prolong the survival time of patients with GCLM and improve the prognosis.

Key words: Gastric cancer, Leptomeningeal metastasis, Clinical features, Prognosis