Pathological Complete Response Achieved with XELOX Chemotherapy, HIPEC, and Anti-PD-1 Immunotherapy in Stage IV Gastric Adenocarcinoma with Peritoneal Metastasis: A Case Report and Review of the Literature

Background: The detection rates of early gastric cancer (GC) in China are approximately 20%; upon diagnosis, the majority of patients with GC are identified as having advanced stage disease, and in some cases, even metastatic advanced GC. Currently, the optimal treatment strategy for peritoneal metastasis (PM) in GC remains uncertain, and pathological complete response (pCR) is rare following conversion therapy. Case presentation: This case report details the management of a 66-year-old patient diagnosed with advanced stage IVB (T4N2M1c) adenocarcinomas of the gastric cardia with PM who received multimodal therapy comprised of hyperthermic intraperitoneal chemotherapy (HIPEC), XELOX chemotherapy, and anti-programmed cell death-1 (PD-1) therapy followed by radical gastrectomy. Through the multimodal management, the patient attained PCR and experienced long-term survival. Conclusion: The conversion therapy protocol combined with HIPEC, XELOX chemotherapy, and anti-PD-1 therapy and our scientific, accurate, full-course management strategy may be propagable for potentially curing patients with advanced GC with PM.