Clinical staging of prostate cancer: An overview

Clinical staging is an assessment of the extent of disease using pretreatment parameters such as DRE, PSA, needle biopsy findings, and radiologic imaging. Pathologic stage, on the other hand, is determined after prostate removal and involves careful histologic analysis of the prostate, seminal vesicles, and pelvic lymph nodes if a lymphadenectomy is performed. Thus, pathologic staging represents a more accurate estimate of the true disease burden and is more useful in the prediction of prognosis. Tumor volume and grade, extracapsular extension, and surgical margins are all accurately determined by pathologic staging. The importance of pathologic stage is underscored by the fact that biochemical recurrence-free survival and cancer-specific survival are both inversely related to the pathologic stage of disease (Figure 43.2). The most important pathologic criteria that predict prognosis after radical prostatectomy are tumor grade, surgical margin status, presence of extracapsular disease, seminal vesicle invasion, and pelvic lymph node involvement.1-7 Two main classification systems for clinical staging exist today: the Whitmore-Jewett and tumor, node, metastasis (TNM) classification systems. Whitmore introduced the first clinical staging classification system for prostate cancer in 1956, and Jewett modified this in 1975.8,9 The TNM system was first adopted in 1975 by the American Joint Committee for Cancer Staging and End Results Reporting (AJCC).10 A new TNM classification system was adopted in 1992 by the AJCC and International Union Against Cancer (UICC) and this system was then modified in 1997 to reduce the subdivision of T2 disease from three categories (T2a, T2b and T2c) to two substages by combining single lobe disease (T2a and T2b) into a single stage (T2).11,12 Several authors have questioned the 1997 modification arguing that the prior distinction between stages T2a and T2b is clinically important.13,14 Table 43.1 summarizes and compares the Whitmore-Jewett and TNM staging schemes.