Improved prognosis of pancreatic cancer patients with peritoneal metastasis.

Abstract Background Peritoneal metastasis is one of the most important poor prognostic factors in advanced pancreatic cancer (PC). Whether the prognosis of PC with peritoneal metastasis has improved with the advent of gemcitabine plus nab-paclitaxel (GnP) and modified FOLFIRINOX (mFFX) is uncertain. The aim of this study was to evaluate the improvements in treatment outcomes of PC with peritoneal metastasis. Methods We retrospectively investigated consecutive PC patients with peritoneal metastasis treated with chemotherapy at our institution between 2010 and 2019. We compared the clinical characteristics and survival outcomes according to the period of diagnosis (group A, 2010–2014; group B, 2015–2019) and chemotherapy regimen. We also examined the prognostic factors for overall survival (OS). Results Among 180 patients included (GnP 88; mFFX 14; other regimens 78), distant metastasis was confined to the peritoneum in 89 patients. Although group B had a worse performance status compared to group A, median OS was significantly longer in group B. GnP and mFFX showed a significantly higher objective response rate and disease control rate in addition to longer progression free survival and OS compared to other regimens. The administration of GnP or mFFX, performance status, and neutrophil to lymphocyte ratio ≥5 were identified as independent prognostic factors for OS. Furthermore, the amount of ascites and extent of peritoneal metastasis were significantly associated with OS in patients with distant metastasis confined to the peritoneum. Conclusions The prognosis of PC with peritoneal metastasis has significantly improved over time with the advent of GnP and mFFX.