The tumor node metastasis (TNM) is the most widely accepted staging system for renal cancer [2]. This approach measures the extent of cancer spread at the primary organ site, regional lymph nodes, and distant sites (Table 4.2). The TNM system underwent considerable revisions over the past three decades with its latest edition (seventh) published in 2010, and a new version is being expected within the next 2 years as of 2015. Purely based on the tumor’s anatomic extent, the different TNM stage categories are lumped into four main prognostic groups (Table 4.3). The clinical (c) stage is routinely used as a guide in determining the type of primary management , such as nephron sparing surgery (NSS) or ablative therapies for low stage renal tumors or systemic therapy for advanced stage tumors. The pathologic (p) stage mainly provides prognosis of outcome after surgical resection of renal cancer and is important on the decision for adjuvant therapy. TNM stage is often incorporated in the inclusion criteria and in stratifying patients for clinical therapeutic trials. The accuracy of TNM stage in renal cancer can be further enhanced by its integration in the different prognostic and predictive models such as the MSKCC prognostic nomogram; the Mayo Clinic stage, size, grade, and necrosis (SSIGN) score; and the UCLA integrated staging system (UISS) [3–7].

In 1958, Flocks and Kasdesky [8] introduced one of the first formal stagings for renal cancer based on the tumor’s anatomic extent and patterns of spread. A year later, Petkovic [9] proposed a similar classification that subdivided intrarenal tumors into stages I and II (Flocks and Kasdesky’s stage I). In the 1960s, Robson modified these systems, incorporated venous involvement, and subdivided localized extrarenal spread [10, 11]. However, Robson’s system was hampered by inaccuracies in some of the stage definitions due to the lumping of prognostically different patterns of anatomic spread [11].

First developed in the 1940s by Pierre Denoix in France, the TNM system was adopted by the Union Internationale Contre le Cancer (UICC) , while the American Joint Commission on Cancer (AJCC) used a slightly different classification. In 1987, the UICC and AJCC were unified, and the first major revision of the TNM staging was published that incorporated tumor size cutoffs derived from cross-sectional imaging studies. Since then, the TNM system underwent several major revisions published in 1993 (supplement), 1997, 2002, and the latest in 2010, building on experiences and evidences accumulated from each prior version in order to enhance its prognostic accuracies (Table 4.4). Revisions in the 2010 TNM system include T2 tumors divided into T2a (>7 cm but ≤10 cm) and T2b (>10 cm); ipsilateral adrenal gland contiguous invasion classified as T4 and, if not contiguous as M1, renal vein involvement reclassified as T3a; and nodal involvement simplified into N0 and N1 [2].