Risk factors for peritoneal recurrence in stage II/III gastric cancer patients who received S-1 adjuvant chemotherapy after D2 gastrectomy.

Abstract

51 Background: Peritoneum is still the most frequent site of the recurrence in stage II/III gastric cancer patients although the survival was improved by S-1 adjuvant chemotherapy. The objective of this retrospective study was to clarify the risk factors of peritoneal recurrence in patients who received S-1 adjuvant chemotherapy. Methods: Peritoneal recurrence free survival (P-RFS) was examined in 100 gastric cancer patients who underwent curative D2 surgery, were diagnosed with stage II or III pathologically, and received adjuvant S-1 between June of 2002 and March of 2011. Uni- and multi- variate analyses were performed to identify risk factors by Cox’s proportional hazard analyses. Results: P-RFS was 64.3% at 3 years and 58.8% at 5 years. A total of 18 patients were diagnosed with peritoneal recurrence. Macroscopic tumor diameter, depth of tumor invasion, and lymph node metastasis were the significant factors by univariate analysis, while tumor diameter and lymph node metastasis were the only significant independent risk factors by multivariate analysis. Conclusions: The macroscopic tumor diameter and lymph node metastasis were the most important risk factors for P-RFS. When patients had these risk factors, S-1 was not sufficient to inhibit peritoneal recurrence. When developing a novel adjuvant chemotherapy targeting peritoneal metastasis in the future, clinical trials should be limited to these patients.