[A Case of Unresectable Locally Advanced Pancreatic Cancer in Which Chemoradiotherapy Achieved Pathological Complete Response].

A 62-year-old man was diagnosed with unresectable locally advanced pancreatic cancer and was treated with mFOLFIRINOX for 9 months. Despite the tumor remarkable shrinkage, the contact with the nerve plexus around the SMA was not diminished. After confirming no distant metastasis with staging laparoscopy, radiotherapy with S-1 was performed. However, even after chemoradiotherapy, CT findings around the SMA showed no significant changes. Eleven months after the initial treatment, conversion surgery was conducted. The nerve plexus was successfully separated from the artery, allowing for a curative resection via pancreaticoduodenectomy. The histopathological findings revealed no residual cancer cells, and post-treatment classification was complete response. The patient remained healthy with no recurrence for over 13 months since the surgical resection. Preoperative CT findings sometimes suggest residual cancer around the nerve plexus even after treatment. However, as this case shows, the suspicion of residual cancer on imaging sometimes reveals no residual cancer, and the final decision may be determined by surgical resection.