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. These
systems are roughly parallel, and comparable stage groups have been set off by
horizontal lines. Surgery is the principal therapy for renal cell carcinoma ;
consequently, both systems include tumors confined within 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.
- The intrarenal pseudocapsule, which is a fibrotic reaction of the peritumoral renal
tissue.
- The renal capsule, which is the fibrous layer on the outer kidney surface. This
structure is absent in the hilar region.
- 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).
- 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 of 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 the main tumor.
Metastasis to 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. The therapeutic contribution of the lymph node dissection
remains controversial.
