Regional therapy trials in peritoneal metastases: The path to standardization of care for gastric cancer.

As the peritoneum is the most common site of metastatic disease at diagnosis, disease identified at staging laparoscopy, and site of recurrence for patients with gastric cancer, intraperitoneal therapy has been an area of interest for many investigators. There are several ways to categorize the existing trials and studies. One is by indication, which includes palliative, neoadjuvant, adjuvant, and prophylactic. Another is by treatment modality which includes approaches such as hyperthermic intraperitoneal chemotherapy, pressurized intraperitoneal aerosol chemotherapy, intraperitoneal normothermic chemotherapy, and bidirectional combinations of systemic and intraperitoneal therapy. Recently completed and ongoing trials of peritoneal therapy in gastric cancer may be improving on the historically dismal survival rates for patients with carcinomatosis or disease at high risk of peritoneal recurrence. All completed randomized trials are from outside the United States, and additional studies of peritoneal therapy in Western populations are needed to clarify survival outcomes. Cooperative group trials and multi-institutional registry study efforts are ongoing to help address this clear area of unmet need.