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Guideline for Cutoff Size For Stage I Renal Cell Carcinoma Should Be Lowered

The Tumor, Nodes, Metastases (TNM) cutoff of 7.0 cm used to separate Stage I from Stage II renal cell carcinoma (RCC) appears to be too high, according to a new report. Instead, a 5.0 cm cutoff appears to stratify size-related survival difference more accurately.

In 1997, the TNM classification of malignant tumour size cutoff between T1 and T2 organ-confined RCC was changed from 2.5 cm to 7.0 cm; however, several investigators have claimed that 7.0 cm may be too high.

Therefore, James M. Elmore, MD, with the University of Texas Southwestern Medical Center, Dallas, United States, and colleagues evaluated the validity of this cutoff size by assessing the survival of patients with Stage I RCC according to a series of alternative size cutoff values. They also determined how these size cutoffs affected the risk of having nonorgan-confined tumours, regional lymph node involvement, and metastatic disease.

The researchers evaluated a database containing the records of 1,324 patients with RCC who underwent open radical nephrectomy between 1960 and 1991. Patients with Stage I disease were stratified by size cutoffs ranging from 2.5 to 7.0 cm in 0.5-cm increments.

A total of 351 out of 544 evaluable patients had tumours of 7.0 cm or smaller, and 233 of these patients had 1997 Stage I (T1N0M0) disease.

When patients with 1997 Stage I tumours were separated based on tumour size, a 5.0-cm cutoff resulted in the most difference in survivals. The 5-year DSS rates for patients with Stage I tumours 5 cm or smaller versus those with tumours measuring 5.1-7 cm were 94.6% versus 79.2% (P = .003). Furthermore, the survival of patients with Stage I RCC lesions measuring 5.1-7.0 cm was the same as for patients with 1997 Stage II (T2N0M0) RCC.

The difference in probability of having local nonorgan-confined disease was also greatest with a 5.0 cm cutoff value (present in 16.2% of the patients with tumours smaller than 5.0 cm compared with 36.8% of the patients with tumours measuring 5.1-7.0 cm in size), which may have an impact on nephron-sparing surgery in selected patients, the authors note.

The difference in the probabilities of having lymph node-positive or metastatic disease did not change significantly using any of the cutoffs, although the probability of both of these increased with increasing tumour size, they report.

"The current study findings, as well as those of others, support a size cutoff for Stage I RCC between 4 cm and 5 cm," the researchers conclude.

Cancer 2003;98:2329-2334. "Reassessment of the 1997 TNM classification system for renal cell carcinoma"

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