Background: According to the GLOBOCAN 2020 results, gastric cancer is the fifth most commonly diagnosed cancer, and fourth most common cause of cancer death worldwide. An estimated 6-27% of patients with gastric cancer show invasion of the adjacent organs at diagnosis. In a previous study, curative resection was shown to significantly improve the prognosis of patients without peritoneal or liver metastases. Herein, we present a case of gastric cancer with invasion of the adjacent organs in a patient who underwent curative surgery. Case presentation: An 80-year-old woman presented with body weight loss and slight fever. Upper gastrointestinal endoscopy revealed Borrmann type 3 gastric cancer extending from the gastric fundus to the corpus. Contrast-enhanced computed tomography (eCT) revealed extensive invasion of the gastric cancer into the transverse colon and pancreas. The eCT also revealed gas in the pancreatic duct, indicating that the gastric lumen was connected to the pancreatic duct because of the tumor. We performed en-bloc tumor resection via total gastrectomy with D2 lymph node dissection, distal pancreatectomy, and partial colectomy. The patient was postoperatively diagnosed with T4b (SI: pancreatic, transverse colon, and splenic serosa), N0 Stage IIIA gastric cancer. The histological type was poorly differentiated adenocarcinoma. Adjuvant chemotherapy was initiated two months after surgery, but was continued for only two months because of severe adverse events. Two years after surgery, the patient remains well. Conclusion: Advanced gastric cancer with extensive invasion of the adjacent organs but no distant metastasis can be treated with en-bloc tumor resection.