Combined Systemic and Intraperitoneal Chemotherapy for Synchronous Gastric and/or Gastroesophageal Peritoneal Carcinomatosis

Patients with peritoneal carcinomatosis from gastric cancer (GPC) have dismal oncologic outcomes, with median survival duration of 6-12 months and 2-year overall survival rate of \< 10%. Despite advancements in systemic therapy, survival remains poor and most patients succumb to the disease within 4-11 months following diagnosis. Therefore, there is a substantial need for novel treatment strategies to improve oncologic outcomes in GPC. The primary intervention is the addition of iterative laparoscopic HIPEC to the ongoing standard systemic chemotherapy regimen (or at least the backbone regimen), based on discussion with their treating medical oncologist. Laparoscopic HIPEC will be performed using a combination of cisplatin (100 mg/m2) and mitomycin C (30 mg total, administered in 2 divided doses of 15 mg each, 45 minutes apart), in 3-liters of normal saline perfusate, at 42°C for 90 minutes, with continuous manipulation of the abdomen to ensure even distribution. Systemic chemotherapy will be administered every two weeks while laparoscopic HIPEC procedures will be performed every 6 weeks in place of the scheduled biweekly systemic therapy cycle. The trial will include a maximum of 3 laparoscopic HIPEC procedures.