The extent of spread of renal cell carcinoma is the dominant factor in prognosis. Two staging systems are widely used for renal cell carcinoma. The system proposed by Robson et al. is compared with the tumor, nodes, metastases (TNM) system. Surgery is the principal therapy for renal cell carcinoma; consequently, both systems include tumors confined by the renal capsule in the most favorable category. A problem comes with the definition of the renal capsule. We have to discriminate 4 different structures forming a capsule surrounding a renal neoplasm.

1. The intrarenal pseudocapsule, which is a fibrotic reaction of the peritumoral renal tissue.
2. The renal capsule, which is the fibrous layer on the outer kidney surface. This structure is absent in the hilar (sinus) region.
3. The perirenal pseudocapsule, which is a fusion product of the former structures with the newly built up perirenal fibrosis. (Beware: perirenal infiltration/penetration can lead to a secondary capsule).
4. Gerota's fascia, which is the fibrous layer covering the perirenal adipose tissue.

In summary, up to 4 fused capsular layers can cover a renal neoplasm. Unlike the Robson system, the TNM system takes size of the tumor into account. Stage III is more complicated and controversial; renal cell carcinoma frequently invades the renal venous system, and this is the criterion Robson stage III A. The prognostic significance of venous invasion has been difficult to establish. Invasion must occur in large veins with smooth muscle in their walls and must be at the edge of...or outside of...the main tumor. Metastasis is said to affect regional lymph nodes without distant metastasis occurs in approximately 10%-15% of cases; but more than 50% of patients with enlarged regional lymph nodes have only inflammatory changes. But, we seldom see nodes removed since so many tumors are now incidentally detected when the abdomen is imaged for other reasons (not tumor symptoms or signs). The therapeutic contribution of the lymph node dissection remains controversial.

Invasion into perinephric soft tissue (pT3) is certain if there is an infiltative border & not certain if merely a pushing border; invasion of the renal vein at the level of the sinus/hilum indicates pT3⁴. Adrenal gland involvement behaves more like a pT4 tumor⁵. Here is a TNM chart.
 

References:

1. essentially copied from John N. Eble, M.D., Indiana University School of Medicine Indianapolis, IN and Stephan Storkel, M.D., University of Witten/Herdecke, Wuppertal, Germany on the USCAP web site 4/24/01.
2. AJCC Cancer Staging Manual (TNM system), 6th Edition, 2002.
3. Rosai & Ackerman's 9th Ed.
4. Assoc. of Directors of AP & SP, "Recommendations for the Reporting of Surgically resected Specimens of Renal Cell Carcinoma", ALCP 131:623-630, May 2009.
5. Urology 2003; http://www.goldjournal.net/article/S0022-5347(05)63851-7/abstract

(posted about 2001; latest addition 16 August 2009)