[Evaluation of classification of pancreatic cancer by the Japan Pancreas Society and Union Internationale Contre le Cancer and proposal for a new international classification].

Different classification systems of pancreatic cancer by the Japan Pancreas Society (JPS, 1996) and Union Internationale Contre le Cancer (UICC) (1997), both of which are based on the TNM system, have been hampering the exchange of data between Japan and Western countries. In the present study, both classifications were assessed using data from 67 patients with invasive ductal carcinoma of the pancreatic head who underwent resection at our clinic. We also propose a new TNM classification and stage grouping system that draws on the merits of both. The results showed that UICC stage grouping did not reflect outcome well, while the JPS system predicted outcome much better. The prognostic value of tha T category is sufficiently reliable in both classifications, but the major drawback of the JPS system is its complex structure and difficult handling. To meet the ideal standard for an international classification system, we propose a new classification: the T category is a minor modification of that of the UICC, and the N category is a modification of that of the JPS for much simpler grouping. Based on the data from our 67 resected patients cases, our new staging system reflects the outcome in the four stages well. Our new classification system may improve the staging classification and lead to the establishment of a more practical and universal staging system for ductal carcinoma of the pancreas.