Pathologic staging of tumors: pitfalls and opportunities for improvements

Stage remains the most important prognosticator of most cancers. In the era of personalized medicine, as the determination of individual characteristics of a given tumor becomes increasingly more important, stage is perhaps one of the best ways to individualize the management of a patient. In the United States, reporting of the American Joint Committee on Cancer/Union for International Cancer Control TNM stage of tumors has all but become a mandate, linked to accreditation of laboratories by College of American Pathologists (CAP), as well as the maintenance of cancer center designations of institutions awarded by the National Cancer Institute and the American College of Surgeons' Commission on Cancer. Providing the stage is now also being considered one of the main "quality indicators" and is linked to reimbursement by insurers. Following suit, many laboratory information system programs have also now integrated CAP synoptic protocols into their software. These regulatory requirements and increasingly widespread usage of staging protocols have also brought to light the imperfections of the current staging protocols. Some are due to the inherent nature of the staging process, which attempts to segregate a continuum (which cancers are) into distinct clusters, which is not always possible. Additionally, although some of the parameters used in staging are evidence-based, many are arbitrary or based on assumptions or logistic progression models. Moreover, some parameters such as the spread of a tumor beyond an organ may seem valid at the theoretic level but are difficult to use in daily practice, for example, for organs without a well-defined capsule. The most problematic issue, however, is the fact that the pathologists are now being asked to incorporate into "pathologic stage" the information that they are not savvy about or cannot verify themselves, such as serum prostate-specific antigen levels or vocal cord paralysis. This current issue of Seminars in Diagnostic Pathology deals with the pitfalls in pathologic staging of common and challenging cancers. In this series of articles written by experts who deal with pathologic staging on daily basis, the authors highlight the problematic aspects of staging in routine practice, discuss the ways these can be dealt with, and also provide a platform for future discussions and improvements in tumor staging.