The relationship between antitumor effects and relative dose intensity of S-1 plus cisplatin treatment for metastatic gastric cancer.

BACKGROUND/AIM S-1 plus cisplatin is the standard first-line chemotherapy for metastatic gastric cancer (MGC) in Japan, but the relationship between dose intensity and antitumor effects remains unclear. PATIENTS AND METHODS We retrospectively studied 64 patients who received S-1 plus cisplatin for MGC from January 2006 to December 2010 in two Japanese hospitals. RESULTS The median relative dose intensity (RDI) of S-1 plus cisplatin was 87% (range, 59.5%-100%). The cut-off value of RDI of S-1 plus cisplatin was identified to be 80% by a receiver operating characteristic analysis of the tumor response. In the RDI<80% (n=19) and the RDI≥80% (n=45) groups, the response rates were 20.0% and 37.5% (p=0.182), the median survival times were 394 and 376 days (p=0.915), and the median progression-free survival (PFS) was 188 and 170 days (p=0.851), respectively. CONCLUSION An appropriate RDI reduction may be permitted for patients with MGC in palliative settings.