Introduction:~Peritoneal metastasis is the most common pattern of gastric cancer recurrence and leads to rapid death. In a previous study, our team established a personalized method which could detect minimal cancer cell DNA in peritoneal lavage fluid with high sensitivity and specificity. We intend to perform a clinical trial to explore the efficacy of intraperitoneal chemotherapy on reducing the incidence of peritoneal metastases in patients with high risk defined by our personalized mutation detection method.~Methods and analysis:~This is a single-arm and single-center clinical trial. Sixty-eight patients with clinical T4 stage gastric cancers will be expected to be enrolled. During surgery, surgeons will wash upper abdominal cavity with 300-400 mL of normal saline before any manipulation of the tumor and collect about 200 mL peritoneal lavage fluid. Cancer cell DNA in peritoneal lavage fluid will be detected by next-generation sequencing using a personalized tumor-specific mutation profiling assay. Patients with positive peritoneal lavage fluid cancer cell DNA will receive adjuvant intraperitoneal chemotherapy in the second month since surgery, then followed by standard adjuvant systemic chemotherapy.~The primary endpoint is the incidence of peritoneal metastasis, and the secondary endpoints include peritoneal metastasis-free survival, disease-free survival (DFS), overall survival (OS), and the safety of intraperitoneal chemotherapy.~Ethics~This trial has been approved by the Ethics Committee of the National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College.
Peritoneal metastasis is a major pattern of gastric cancer recurrence and predicts poor prognosis. In our previous study, we developed a next-generation sequencing technology to detect minimal residual cancer cells in peritoneal lavage fluid with a personalized assay profiling tumor-specific mutations in patients with gastric cancer. With this technology, we predicted all the cases that developed peritoneal metastasis in patients with pT4 disease with 100% sensitivity and 91% specificity. Based on this result, a prospective phase 2 clinical trial is designed to evaluate the efficacy of adjuvant intraperitoneal chemotherapy in patients with positive cancer cell DNA detected in peritoneal lavage fluid by our personalized tumor-specific mutation profiling assay.