Oligometastasis of Gastric Cancer: A Review

Simple Summary Oligometastatic cancer describes an intermediate stage of cancer between localized and widely spread disease. Oligometastasis can be treated with local treatments, such as surgical removal or radiotherapy. The concept of oligometastasis is also observed in the field of gastric cancer. However, the definition of oligometastasis in gastric cancer is not yet established. Metastatic lesions that are localized and technically removable at diagnosis and that demonstrate a certain response to chemotherapy sometimes present a favorable survival outcome with local treatment. Those metastatic lesions are considered oligometastasis in the field of gastric cancer. Major guidelines for gastric cancer describe the concept of oligometastasis, and a European multicenter board of experts organized the OligoMetastatic Esophagogastric Cancer Consortium to establish the definition, diagnosis, and treatment for oligometastasis. Two large phase 3 studies are ongoing to evaluate the survival outcomes of patients with oligometastasis treated with perioperative chemotherapy combined with surgical removal.Abstract The concept of oligometastasis is not yet fully established in the field of gastric cancer. However, metastatic lesions that are localized, technically resectable at diagnosis, present a certain response to preoperative chemotherapy, and present favorable survival outcomes with local treatments, sometimes in combination with chemotherapy, are recognized as oligometastasis in the field of gastric cancer. Oligometastasis is noted in European Society for Medical Oncology guidelines and Japanese gastric cancer treatment guidelines, and local treatment is mentioned as one of the pivotal treatment options for oligometastasis. Solitary liver metastasis or a small number of liver metastases; retroperitoneal lymph node metastasis, especially localized para-aortic lymph node metastasis; localized peritoneal dissemination; and Krukenberg tumor are representative types of oligometastasis in gastric cancer. The AIO-FLOT3 trial prospectively evaluated the efficacy of multimodal treatments for gastric cancer with oligometastasis, including surgical resection of primary and metastatic lesions combined with chemotherapy, confirming favorable survival outcomes. Two phase 3 studies are ongoing to investigate the efficacy of surgical resection combined with perioperative chemotherapy compared with palliative chemotherapy. Thus far, the evidence suggests that multimodal treatment for oligometastasis of gastric cancer is promising.