The pathology of bladder cancer.

Pathologists play an important role in the management of urinary bladder cancer by making a careful morphologic assessment of the primary tumor and its relation to adjacent structures. Ideally, evaluation of the primary site will segregate patients into groups with distinct clinical features, biologic behavior, and response to therapy. Traditionally, to accomplish this goal, pathologists have relied on factors such as histologic tumor type, grade, depth of invasion, and presence or absence of vascular invasion. Recently, in an effort to enhance our ability to subclassify these patients, we have introduced new modalities, such as flow cytometry, monoclonal antibodies, assessment of proliferative rate, and cytogenetics and molecular genetics. Without question we are advancing into an era in which tumors will be classified based on their molecular "fingerprint." Nevertheless, at this time, morphology remains the "gold standard" and, consequently, the best tool to assess the biologic potential of early bladder cancer. Despite this undeniable fact, there are many problems with the pathologic evaluation of these tumors, mostly because of the inherent subjectivity of the field and the lack of universal, standardized criteria for the evaluation of the above-mentioned morphologic parameters. Publications in peer-reviewed journals and the proliferation of educational opportunities by way of seminars, conferences, and web-based tutorials play an important role in keeping the practicing pathologist informed and up to date. As novel concepts and modern techniques are reported, their clinical value must be validated prospectively. Expert pathology review and establishment of exportable practice standards play an important role in the process.