The coauthors of this article were all involved with this conference and consequently created an international group to overcome this shortcoming by working on a new staging system. Recently, a group of experts16 proposed a new staging system for IHC; the various grades were validated with a large database available in the United States. In this article, we focus on PHC, the most common and challenging form of CCA. Our aim is to propose a simple, reproducible, easily applicable, find protocol and informative staging system. To achieve

this goal and enable international acceptance, the staging will be established by the consensus of a group of international experts in the field. First, we discuss the need for a staging system. Next, we review the currently available staging systems. Then, we present the information needed to establish a valuable staging system. Finally, we submit our proposal for a new staging system. In contrast to IHC, it is currently not possible to test the ability of the new staging system to predict the natural history of the disease or the outcome after surgery because this information is not available in any large database. Our goal, therefore, is to offer a descriptive

system that will enable us to test correlations of various tumor characteristics with survival or other outcomes once a prospective database is available. Upon the publication of this article, we will open a professionally designed, online-based registry for PHC that is based on the new proposal www.cholangioca.org. A staging system PARP inhibitor for patients with cancer must ideally (1) provide information about the prognosis and natural history of the disease, (2) serve as a guide for therapy, and (3) enable convincing comparisons of therapies among various institutions and over time.17 In so-called surgical diseases, a staging system is crucial for deciding between an aggressive approach (i.e., chance for cure) and only palliative alternatives. Another criteria for a good

staging system is its ability to identify patients for the best type of surgery (e.g., local resection versus extensive Quinapyramine resection or even liver transplantation). Staging systems for cancer usually describe the extent of the disease according to the primary tumor and its spread. The tumor-node-metastasis (TNM) classification is the gold standard for many cancers because it is simple to understand, applies to many types of cancers, and provides information on the primary tumor (T), the lymph node status (N), and distant metastases (M).17, 18 Unfortunately, this system is of little help when local factors, such as the precise localization of the tumor along the bile duct, are crucial to predicting the natural history of the disease and choosing the therapy.