Free Peritoneal Cancer Cells in Patients with Adenocarcinoma of The Stomach or Esophagogastric Junction: Risk Factors and Outcomes

Background/Objectives: To identify independent predictors of free peritoneal cancer cells (FPCC), and to investigate survival outcomes relative to peritoneal cytology status among patients underwent intended curative gastrectomy for adenocarcinoma of stomach or esophagogastric junction. Methods: Medical record of patients underwent radical surgery during January 2005-December 2020 were retrospectively reviewed. Clinical data and cytology results were evaluated. Multivariate Cox regression analysis was used to identify independent predictors of FPCC. Kaplan-Meier survival analysis was used to estimate disease recurrence and survival outcomes. Results: Of the 349 enrolled patients, 188 (53.8%) had negative cytology, 32 (9.2%) had positive cytology, and 129 (36.9%) had atypical cells in peritoneal cytology. Multivariate analysis revealed poor differentiation (adjusted odds ratio [aOR]: 2.63, 95% confidence interval [95%CI]: 1.04-6.82; p=0.015), pT4 (aOR: 4.62, 95%CI: 1.28-14.34; p=0.018), pN3 (aOR: 4.13, 95%CI: 1.14-15.03; p=0.031), and metastatic lymph node ratio >0.40 (aOR: 6.49, 95%CI: 1.44-29.14; p=0.015) as independent predictors of FPCC. Median survival duration of patients with negative, positive, and atypical cell cytology was 34.1, 13.1, and 28.7 months, respectively (p<0.001). 5-year OS was 27.2%, 8.3%, and 25.3%, respectively (p<0.001). 3-year DFS was 17.8%, 0.0%, and 17.4%, respectively (p<0.001). Median time to disease recurrence was 20.5, 4.9, and 11.3 months, respectively (p<0.001). Survival outcome and disease recurrence were comparable between atypical cell and negative peritoneal cytology patients. Conclusions: Poorly differentiated histology, pT4, pN3, and metastatic lymph node ratio >0.40 are independent predictors of FPCC. The presence of FPCC was significantly associated with poor survival and disease recurrence outcomes.