Reassessing the Current UICC/AJCC TNM Staging for Renal Cell Carcinoma

Context: The outcome prediction for renal cell cancer (RCC) remains controversial, and although many parameters have been tested for prognostic significance, only a few have achieved widespread acceptance in clinical practice. The TNM staging system defines local extension of the primary tumour (T), involvement of regional lymph nodes (N), and presence of distant metastases (M). Objective: This review focuses on reassessing the current TNM staging system for RCC. Evidence acquisition: A literature search in English was performed using the National Library of Medicine database and the following keywords: renal cell cancer, kidney neoplasm, and staging. We scrutinized 1952 references, and 62 were selected for review based on their pertinence, study size, and overall contribution to the field. Evidence synthesis: The prognostic significance of tumour size for localized RCC has been investigated in a large number of studies. As a consequence, many modifications of the TNM staging system were primarily made to the size cut points between stage I and II tumours. The latest three revisions of the TNM system are systematically reviewed. For the heterogeneous group of locally advanced RCCs, involving different anatomic structures surrounding the kidney, the situation is still the subject of controversial scientific dispute. In detail, perirenal fat invasion, direct infiltration of the ipsilateral adrenal gland, invasion of the urinary collecting system, infiltration of renal sinus fat, and vena cava and renal vein thrombosis are disputed. Finally, staging of lymph node metastases and distant metastatic disease is discussed. Conclusions: Special emphasis should be put on renal sinus invasion for stage evaluation. Retrospective studies relying on material collected at a time when no emphasis was placed on adequate sampling of the renal sinus should be treated with caution. In view of new treatment opportunities, the current TNM staging system of RCC and any other staging system must be dynamic.