Comparison of S-1 and S-1 plus cisplatin as post-operative chemotherapy for gastric carcinoma with peritoneal lavage cytology positive or localized peritoneum metastasis: A multicenter retrospective study.

Abstract

109 Background: Peritoneal lavage cytology of class V and localized peritoneum metastasis of gastric cancer (GC) are defined as CY1 and P1 in the 14th edition of the Japanese Classification of GC. Because patients (pts) with CY1 and/or P1 have poor prognosis after resecting all macroscopically visible disease by standard surgical resection, post-operative chemotherapy (post-Cx) is commonly performed in the clinical practice in Japan. However, no standard chemotherapy has not been established. The aim of this study was to investigate the efficacy of post-Cx in patients with CY1 and/or P1. Methods: We retrospectively reviewed the GC pts who were diagnosed to have CY1 and/or P1 at 34 institutions participating in the Stomach Cancer Group of Japan Clinical Oncology Group between 2007 and 2012. Inclusion criteria were: PS 0-2, histology of adenocarcinoma, no distant metastasis other than CY1 or P1, no prior treatment for GC. The subject of this study was the patients who received surgery followed by post-Cx. Results: A total of 824 pts were collected from 34 institutions. Of the 506 eligible pts, 444 pts underwent standard gastrectomy followed by post-Cx: S-1 (n=267), S1 plus cisplatin (SP) (n=114) or others (n=63). 62 pts did not receive post-Cx (non-Cx). Median age for the S1/SP/Others/non-Cx group were 69/63/66/75. In the S-1 group, pts with P0CY1/P1CY0/P1CY1 were 197/44/26, and those were 81/21/12 in SP, 45/9/9 in Others, and 44/7/11 in non-Cx. Conclusions: Post-Cx may have survival benefit after surgery for GC with CY1 or P1, while there seems no additional benefit over S-1. [Table: see text]