Japanese Pancreas Society Staging Systems for Pancreatic Cancer

Abstract

Both Japan Pancreas Society (JPS) staging system and International Union Against Cancer (UICC) staging system adopt TNM classification, however, there are considerable differences in detail. Regarding the T category, a tumor involving only the intrapancreatic bile duct is classified as UICC T1 or T2 tumor, but as JPS T3. Most of resectable tumors are altogether classified into UICC T3, however, into JPS T3 or T4. Invasion to extrapancreatic nerve plexus (PL) is treated as JPS T4, but as UICC T3. Since massive perineural invasion to PL around the major artery often causes encasement of the artery, it might be recommended in the future revision that UICC T4 definition should be interpreted as ``Tumor involves CA, SMA, or PL around these arteries.'' The N category in the UICC staging system is quite simple as N0 or N1 indicating positive regional nodes. In the JPS staging system, N1; N2; and N3 correspond to metastasis to lymph nodes that are unintendedly removed altogether with the pancreas during pancreatoduodenectomy or distal pancreatectomy; regional nodes that are resected with intent of curative lymphadenectomy; and distant lymph nodes that are rarely included for curative lymphadenectomy, respectively.