Staging of advanced bladder cancer. Current concepts and pitfalls.

SUMMARY Data presented in the preceding paragraphs should highlight to the reader several important features of clinical bladder cancer staging. Irrespective of the staging level being addressed, the available techniques uniformly have limitations, as well as advantages and disadvantages with respect to each other. A common shortcoming of both plain and cross-sectional techniques employing conventional X-rays is their lack of specificity. Every radiographic finding has an associated differential diagnosis in which neoplasia-related change is but one of many possibilities. Solitary abnormalities on bone scan or chest film serve as an excellent examples of this dilemma. The specificity of conventional imaging techniques is further compromised by attempts to increase sensitivity. As long as nonspecific anatomic changes are used as discriminating criteria, increases in test sensitivity will always occur at the price of specificity. It is hoped that advances in PET scanning and the use of isotope-labeled, tumor-selective monoclonal antibodies will overcome the limitations of currently available techniques. The significance of the limitations of a given test depends to some degree on whether the test is being used for clinical decision making or for patient stratification in a clinical trial. As an example, an aggressive transurethral resection of bladder tumors provides excellent information for clinical management but may introduce bias into multicenter studies in which this technique is not uniformly practiced. Similarly, the results of bimanual examination under anesthesia are important in the reference framework of the managing physician but are a poor quantifier of disease extent in multi-investigator clinical trials. Which staging studies are indicated and their optimal sequence for performance are influenced by pre-existing clinical information. Recognizing this, the staging algorithm in Figure 6 is intended to serve only as a guide to assist the clinician in the evaluation of patients with bladder neoplasms. As clarifications, several points concerning this algorithm merit mention. The literature suggests that as a single study, transurethral ultrasonography provides excellent local staging information. However, given that it is not widely available, the authors have chosen not to incorporate it into the staging schema. Optimally, it would be used immediately prior to transurethral resection of bladder tumors and bimanual examination. In addition, the algorithm lists MRI interchangeably with CT. While MRI appears to have slightly better sensitivity and specificity for both local and regional tumor stage relative to CT, its benefits are to some degree offset by its greater cost and the need to image the patient in multiple planes for lengthy intervals. At this time, the authors limit their use of MRI to cases which are equivocal based on information obtained from CT and bimanual examination. As a final note, we obtain a chest radiograph early in the evaluation of patients with invasive tumors. It is both disheartening and humbling to expend large amounts of time and resources in staging the disease only to discover pulmonary metastases on a chest film performed subsequent to the sophisticated staging studies. In interpreting the results of staging studies, it is critical to recognize that no test functions well in a vacuum of clinical data. Test sensitivities and specificities provide us with statements of statistical probability, which, while applicable to populations of patients, cannot stand alone in the individual patient. In order to optimize the interpretation of imaging studies, our radiologic colleagues must be provided with an adequate patient history. As managing physicians, we must then integrate each new test result into the existing database of clinical information. Ultimately, decisions regarding test relevance and accuracy are based on an understanding of test sensitivity and specificity in concert with the sum of collaborative clinical data from the individual patient.