Prognostic and Predictive Factors for Patients With Gastric Cancer who Are Positive for Peritoneal Lavage Cytology and Negative for Other Distant Metastasis

Background/Aim: This study aimed to clarify the prognostic and predictive factors of patients with gastric cancer (GC) who are peritoneal lavage cytology positive and negative for other distant metastasis. Patients and Methods: Consecutive patients were selected from the database of Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Department of Gastric Surgery, Tokyo, Japan, according to the following criteria: i) histologically-proven gastric adenocarcinoma; ii) patients who underwent macroscopically curative gastrectomy for gastric cancer as a primary treatment; and iii) a diagnosis of peritoneal washing cytology positive (CY1) disease with no distant metastasis between 2005 and 2025. Results: A total of 89 patients were eligible for the present study. One-, three- and five-years overall survival (OS) rates of the whole cohort were 68.6%, 41.2%, and 21.3%. Medina survival time was 22.2 months (range=11.3-33.1 months). In the prognostic analysis for OS in the CY positive patients with GC who were negative for other distant metastasis, postoperative chemotherapy status was one of the independent prognostic factors [hazard ratio (HR)=2.228, 95% confidence interval (CI)=1.330-3.734]. One-, three- and five-years OS rates of the patients with postoperative adjuvant chemotherapy were 81.1%, 46.3%, and 33.9%, while that of patients without postoperative chemotherapy were 47.6%, 32.9%, and 4.7% (p=0.001). In addition, the prognostic analysis for OS in the CY positive patients GC who were negative for other distant metastasis and received postoperative chemotherapy, lymph node metastasis status was an independent significant prognostic factor in multivariate analysis (HR=6.312, 95% CI=1.476-26.996, p=0.013). Conclusion: Postoperative chemotherapy improved the survival of CY positive patients with GC who were negative for other distant metastasis. In addition, lymph node metastasis status was an independent prognostic factor for CY positive patients with GC who were negative for other distant metastasis and received postoperative chemotherapy.