Treatment outcomes of systemic chemotherapy for peritoneal carcinomatosis arising from gastric cancer with no measurable disease: Retrospective analysis from a single center

Background: Few studies of systemic chemotherapy have focused on gastric cancer with peritoneal carcinomatosis (PC) without measurable lesions. In the present study, we characterized the outcomes of systemic chemotherapy and prognostic factors for gastric cancer with PC, particularly in patients without measurable disease. Methods: Clinical data from 211 gastric cancer patients with PC (137 without and 74 with measurable disease) who had received systemic chemotherapy between January 2003 and December 2010 at a single center were reviewed. Results: The median overall survival (OS) rate of gastric cancer patients with PC with no measurable disease was significantly longer than that of patients with measurable disease (18.0 vs. 11.6 months, p = 0.010). On multivariate analysis, poor performance status [hazard ratio (HR) = 2.15, p < 0.001], the presence of metastatic lymphadenopathy (HR = 2.17, p < 0.001), and high-grade PC (HR = 1.83, p = 0.001) were associated with significantly decreased OS. When patients with low-grade PC were stratified by clinical PC grade, the median OS of those without measurable disease was 19.6 months. The median OS of patients with low-grade PC with no measurable disease was longer than those of patients with high-grade PC without measurable disease, patients with low-grade PC with measurable disease, and patients with high-grade PC with measurable disease (p = 0.001, p = 0.029, and p < 0.001, respectively). Among the patients with low-grade PC, patients who received a gastrectomy had longer survival than patients who did not receive a gastrectomy (p < 0.001). Conclusions: In our study, clinically low-grade PC without measurable disease was associated with better outcomes of systemic chemotherapy than the outcomes in the other groups examined. Clinical trials in patients with gastric cancer with PC should be stratified according to PC grade.