[Conversion Surgery for Pancreatic Cancer]

Pancreatic cancer is known as a disease with an extremely poor prognosis. Although surgery is the only curative treatment, most pancreatic cancer is already advanced at the time of diagnosis. With advances in multidisciplinary treatment such as chemotherapy, radiation therapy, and heavy-ion therapy, more cases of unresectable(UR)pancreatic cancer are being treated with surgery in recent years. Therefore, the term"conversion surgery"has been newly included in the 8th edition of the General Rules for Study of Pancreatic Cancer, and the treatment strategy for UR pancreatic cancer has entered a new phase. Conversion surgery for UR-LA pancreatic cancer is expected to be effective as the indications for chemoradiation and heavy-ion radiation therapy expand. On the other hand, UR-LA pancreatic cancer is not only a locally advanced disease but also a systemic disease, and there have been reports of patients with early postoperative recurrence, so the indication for surgery remains a controversial field. Furthermore, there are increasing reports of conversion surgery for UR-M pancreatic cancer. There are concerns about complications and increased mortality due to extended resection, and early recurrence, so usefulness is not clear at present. Among UR-M, positive peritoneal washing cytology(CY1)is considered to be a preliminary stage of peritoneal dissemination, and is now treated as distant metastasis since the 8th edition of General Rules. CY-positive pancreatic cancer is easier to control than other distant metastases, and CY-negative conversion is expected to be equivalent to that of patients with CY0 at the initial diagnosis. Further evidence for multidisciplinary treatment, including conversion surgery, is expected to be accumulated.