Recent active surveillance studies where renal masses are observed over time have suggested that small renal tumors grow at a fairly slow and predictable rate, thus suggesting that observation represents a reasonable approach in patients with small renal masses, particularly in those where surgical intervention may be associated with significant risk of morbidity and mortality. Here, Remzi and colleagues examine the relationship between tumor size and unfavorable histopathological variables in a cohort of patients with small renal masses.

The authors identified 287 kidneys with tumors ? 4 cm in their surgical series. Of these, 95.1% were localized and 4.9% were metastatic. Mean tumor size was 2.94 cm with 22.6% ? 2 cm, 35.9% 2.1 - 3 cm, and 41.5% 3.1 - 4 cm. While 19.5% of the tumors were benign, RCC was found in 227 (70% clear cell, 20.7% papillary, 4.8% chromophobe) and 13.6% had multifocal disease. Multifocal disease correlated with larger tumor diameter (p=0.048) and the presence of papillary histology (p=0.018). The authors found that increasing tumor diameter was significantly associated with higher grade (p=0.0007) and higher stage (p=0.0023), especially in the group of patients with tumor size greater than 3 cm. While only 4 patients with tumor size ? 3cm had metastatic disease, metastases were found in 10 (8.4%) of patients with tumors 3.1 - 4 cm (p=0.045).

The authors conclude that the malignant potential of small RCC tumors increases significantly when their size exceeds 3 cm. Given that it can be difficult to measure changes in tumor diameter with sequential imaging studies, the authors argue that the criteria for entering patients in to observational or active surveillance studies should be well below this 3 cm benchmark.

Remzi M, Ozsoy M, Klingler HC, Susani M, Waldert M, Seitz C, Schmidbauer J, Marberger M

J Urol 176: 896-899, 2006

Written by Christopher G. Wood, MD, a Contributing Editor with UroToday.

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