Is the UICC/AJCC pT2 Staging Category for Clear Cell Renal Cell Carcinoma Meaningful?

Abstract

This study was undertaken to determine the association between extrarenal tumor spread and size in a series of well-sampled clear cell renal cell carcinoma (ccRCC). In a series of 917 cases of ccRCC, 178 were >7 cm in maximum extent. Assessment of tumors >7 cm in size showed 72 (40.4%) to have renal sinus infiltration, the tumor infiltrating perirenal fat in 7 (3.9%) cases, and both in 96 (53.9%) cases. In the remaining 3 (1.7%) cases, no extrarenal extension of the tumor was seen. These 3 cases with organ-confined ccRCC were all cystic tumors. Two showed extensive infarction with associated hemorrhage and the presence of a thick investing pseudocapsule, while the third was a cystic ccRCC arising in the upper pole of the kidney. For the ccRCCs in the series that were ≤7 cm in maximum extent, division of cases according to tumor size and pT staging category showed an increase in the proportion of tumors showing extrarenal spread with increasing size, ranging from 0% for tumors <1 cm in diameter to 84.7% for tumors >6 to 7 cm. The study has shown that for ccRCC, the extrarenal spread of tumor is strongly associated with the size of the primary tumor. The study has also shown that renal sinus invasion and/or perirenal fat infiltration by tumor is commonplace in tumors >7 cm in maximum extent and that tumors of this dimension are rarely organ-confined. These findings provide evidence that the defining features of pT1, pT2, and pT3a staging categories for ccRCC require revision.