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 who underwent intended curative gastrectomy for adenocarcinoma of the stomach or esophagogastric junction. Methods: Medical records of patients who underwent radical surgery between January 2005 and 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: Out of the 349 enrolled patients, 188 (53.8%) had negative cytology, 32 (9.2%) were positive, and 129 (36.9%) showed atypical cells in peritoneal cytology. 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) were independent predictors of FPCC. Median overall survival was 34.1 months in the negative group, 13.1 months in the positive group, and 28.7 months in the atypical cell group (p < 0.001). Median time to disease recurrence was 20.5, 4.9, and 11.3 months, respectively (p < 0.001). Survival and recurrence outcomes in the atypical cell group were comparable to those with negative cytology. Conclusions: Poorly differentiated histology, pT4, pN3, and metastatic lymph node ratio >0.40 are independent predictors of FPCC, which is significantly associated with poor survival and disease recurrence outcomes. These findings suggest that high-risk patients may benefit from routine peritoneal cytologic screening during surgery to improve risk stratification and guide postoperative treatment planning.