Survival benefit of intravenous and intraperitoneal paclitaxel with S-1 in pancreatic ductal adenocarcinoma patients with peritoneal metastasis: a retrospective study in a single institution.

Background We evaluated the clinical efficacy of intravenous (i.v.) and intraperitoneal (i.p.) paclitaxel (PTX) combined with S-1 in patients with chemotherapy-naive pancreatic ductal adenocarcinoma (PDAC) with peritoneal metastasis. Methods Forty-nine patients were diagnosed with peritoneal metastasis during 2007–2014; 29 received gemcitabine or S-1-based chemo(radio)therapy from 2007 to 2011 (control group), and the remaining 20 received i.v. (50 mg/m2) and i.p. (20 mg/m2) PTX on days 1 and 8, and S-1 at 80 mg/m2 per day for 14 consecutive days, followed by 7 days of rest from 2012 to 2014 (study group). Results The median survival time in the study group was significantly longer than that in the control group (20 vs. 10 months, respectively; P = 0.004). At 1 year after initial treatment, a significant difference in ascites development on CT was found between the study (5/20 patients) and the control group (18/29 patients, P = 0.009). The frequency of objective response (9/20 patients) and conversion surgery (6/20 patients) in the study group was higher than those in the control group (8/29 and 2/29, respectively). Patients who underwent conversion surgery had improved survival in both groups. Conclusion Implementation of the S-1+i.v./i.p. PTX regimen was closely associated with improved overall survival in PDAC patients with peritoneal metastasis.