Amendment to renal cancer TNM staging proposed

By Eleanor McDermid, Senior medwireNews Reporter

Patients with pT3a renal cell carcinoma (RCC) have markedly worse survival rates if they have both fat invasion and renal vein thrombosis, rather than just one of these factors, a study shows.

“We believe that fat or renal vein invasion alone or in combination should be used as a criterion for staging in a future edition of the TNM classification, because the oncologic outcomes seem to be significantly dissimilar after a long-term follow-up,” say lead researcher Marco Borghesi (University of Bologna, Italy) and colleagues.

“To confirm these interesting results and suggest modifications to the current TNM staging system, an international, multi-institutional collaborative study is needed.”

The researchers based their conclusions on an average 41.7 months of follow-up of 122 retrospectively identified patients with pT3a RCC who underwent radical or partial nephrectomy.

“Despite all the modifications of the TNM staging system over the past years, the optimal classification of RCC remains controversial because the stratification of outcomes in T3 category is particularly challenging,” they comment in Clinical Genitourinary Cancer.

Of the patients, 51.6% had tumors with invasion of perirenal fat or sinus fat, 14.7% had tumors with renal vein thrombosis, and 33.6% had tumors with both fat invasion and vein thrombosis.

These groups had no significant baseline differences in clinical or pathologic variables, yet the 5-year cancer-specific survival rates were 69% for patients with just one of the two prognostic variables compared with 40% for those with both. The corresponding 10-year rates were 62% and 33%.

On multivariate analysis, patients with both fat invasion and renal vein thrombosis were 1.89-fold more likely to die of their cancer than those with just one of these factors.

Pathologic tumor size, higher M stage and Fuhrman grade, positive surgical margins, and the presence of sarcomatoid differentiation were also independent predictors for cancer-specific mortality.

“Thus, taking in consideration our retrospective analysis, we assume that patients with pT3a RCC as defined by the actual TNM classification should not be considered as a single prognostic group,” say Borghesi et al.

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