Factors predicting peritoneal recurrence in advanced gastric cancer: Implication for adjuvant intraperitoneal chemotherapy

Background: Despite adjuvant chemotherapy, patients with advanced gastric cancer (AGC) often develop recurrence, and the peritoneum is the most common site of recurrence. Therefore, intraperitoneal chemotherapy (IPC) has been proposed as a treatment option. The aim of this study was to select the eligible patients for application of IPC. Methods: A total of 805 patients with AGC who underwent curative D2 gastrectomy between May 2003 and December 2009 were included in this study. Risk factors for peritoneal recurrence were analyzed. Results: Recurrence developed in 245 patients (30.4 %). The first site of recurrence was the peritoneum in 144 patients (58.8 %), and the 5-year peritoneal recurrence-free survival was 79.3 %. Depth of tumor invasion ≥T3, extensive lymph node metastasis (N3), Bormann type 4, infiltrative type (Ming's classification), and venous invasion were independent risk factors for peritoneal recurrence. In subgroup analysis with patients who had received adjuvant chemotherapy (n = 481), depth of tumor invasion ≥T3, Bormann type 4, infiltrative type (Ming's classification), and venous invasion were independent risk factors for peritoneal recurrence. When a peritoneal recurrence risk index was made with each risk factor assigned 1 point (2 points for T4 stage), peritoneal recurrence rates with 0, 1, 2, 3, 4, or 5 points were 0 %, 3.9 %, 13.1 %, 33.3 %, 44.0 %, and 72.0 %, respectively, in those patients. Conclusions: Patients at higher risk for peritoneal recurrence can be identified from the findings of this study. Further prospective studies are required to evaluate the usefulness of IPC for these patients.