2016 SSAT PLENARY PRESENTATION Conversion Surgery Post-Intraperitoneal Paclitaxel and Systemic Chemotherapy for Gastric Cancer Carcinomatosis Peritonei. Are We Ready? Dexter Yak Seng Chan 1 & Nicholas Li-Xun Syn 2,3 & Rachel Yap 2 & Janelle Niam Sin Phua 1 & Thomas I. Peng Soh 2 & Cheng Ean Chee 2 & Min En Nga 4 & Asim Shabbir 1 & Jimmy Bok Yan So 1 & Wei Peng Yong 2 Received: 27 May 2016 /Accepted: 23 November 2016 # 2016 The Society for Surgery of the Alimentary Tract Abstract Peritoneal metastasis is common in gastric cancer. It is difficult to treat and carries a poor prognosis. Intraperitoneal (IP) delivery of chemotherapy can attain a higher drug exposure in the peritoneal cavity but with reduced systemic toxicity. Therefore, we hypothesized that IP paclitaxel with systemic chemotherapy would be clinically beneficial for gastric cancer with peritoneal metas- tases. Patients with unresectable and/or recurrent gastric adenocarcinoma with peritoneal dissemination and/or positive peritoneal washing cytology were recruited. They underwent eight cycles of IP paclitaxel and systemic XELOX. The primary endpoint was 1- year overall survival rate and secondary endpoints were safety, response rate, and peritoneal cytological response. Patients who subsequently had no distant metastases and two consecutive negative peritoneal cytologies underwent conversion gastrectomy if there was no macroscopic evidence of peritoneal disease at diagnostic laparoscopy. Twenty-two patients were enrolled, receiving at least one cycle of IP paclitaxel at the time of reporting (data cutoff—March 11, 2016). The median number of cycles was 7.5. The median overall survival was 18.8 months, and the 1-year survival rate was 72.2%. One patient died of neutropenic sepsis. Of 19 evaluable patients with measurable disease, 7 (36.8%) achieved PR, 8 (42.1%) achieved SD, and 4 (21.1%) experienced PD. Peritoneal cytology turned negative in 11 of 17 (64.7%) patients. Six patients underwent conversion gastrectomy (4 R0, 2 R1) with a median survival of 21.6 months (range = 8.7–29.9 months). XELOX and IP paclitaxel appears to be an effective regimen in gastric cancer with peritoneal metastases. Conversion gastrectomy may be considered in patients with a favorable response. Keywords Intraperitoneal chemotherapy . Gastric cancer . Peritoneal metastases Introduction Carcinomatosis peritonei is one of the most common and most debilitating forms of metastases in patients with gastric cancer. Despite advances in multimodal therapy, survival is poor with limited response from systemic chemotherapy. 1–4 A possible explanation for this is the peritoneal blood barrier which prevents a high concentration of intravenous chemo- therapy from penetrating peritoneal metastases in high con- centrations. Hence, it is believed that intraperitoneal (IP) administration of chemotherapeutic drugs enables an ade- quately high concentration to directly impact these perito- neal deposits. However, the administration of IP Mitomycin C or cisplatin in clinical studies yielded no apparent thera- peutic effects due to brisk absorption of the drug through the peritoneum. 5 In contrast, due to its large molecular weight, absorption of paclitaxel is delayed through the lymphatic system after IP administration. IP administration of pacli- taxel was developed to enhance antitumor activity against This paper was presented at Digestive Diseases Week 2016 on May 22, 2016 and at the 31st Annual SSAT Residents and Fellows Research Conference on May 21, 2016 in San Diego, CA, USA. * Jimmy Bok Yan So jimmy_so@nuhs.edu.sg 1 Department of Surgery, National University Health System, 1E Kent Ridge Road, NUHS Tower Block, Level 8, Singapore 119228, Singapore 2 Department of Haematology–Oncology, National University Cancer Institute, Singapore, Singapore 3 Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore 4 Department of Pathology, National University Health System, Singapore, Singapore J Gastrointest Surg DOI 10.1007/s11605-016-3336-3