[A Rare Case of Radical Resection for the Synchronous Double Cancer of Primary Pancreatic Squamous Cell Carcinoma and Primary HER2-Positive Gastric Cancer after Multidisciplinary Treatment].

A 69-year-old man was referred to our hospital due to a rapid increase of HbA1c. Computed tomography(CT)showed a 40 mm hypo vascular tumor in the body of the pancreas, which was diagnosed as pancreatic squamous cell carcinoma by endoscopic ultrasound-fine needle aspiration. Also, esophagogastroduodenoscopy(EGD)revealed a type 2 tumor in the body of the stomach, which was diagnosed as well differentiated gastric cancer. Gemcitabine and S-1(GS)was performed for pancreatic cancer as neoadjuvant chemotherapy. Both pancreatic and gastric cancer were reduced in size once. However, after 9 courses, CT and EGD showed increase in size of gastric cancer. Trastuzumab plus capecitabine and oxaliplatin, followed trastuzumab plus S-1 and oxaliplatin(SOX), was employed for gastric cancer. While the gastric cancer was remarkedly reduced, the pancreatic cancer was increased in size. GS was administered again, but both pancreatic and gastric cancer were increased in size. Finally, trastuzumab plus SOX was employed for gastric cancer, and 60 Gy of radiotherapy followed nab-paclitaxel and gemcitabine(GA)was employed for pancreatic cancer. After that, distal pancreatectomy, total gastrectomy, splenectomy, and cholecystectomy were performed for pancreatic and gastric cancer. Histopathological findings revealed pancreatic squamous cell carcinoma, ypT3N0M0, and pathological response is Grade 2, also gastric cancer, ypT3 N0M0, and pathological response is Grade 2a. Adjuvant chemotherapy with S-1 was administered and is still ongoing.