Small Kidney Tumors Potentially Dangerous, Worth Treating

Even those renal cell carcinomas (RCCs) that are smaller than 4 cm may put patients at risk for aggressive cancer, according to a new study presented at the 28th Annual European Association of Urology Congress in Milan, Italy.

Serial CT image of renal cell carcinoma with growth in VHL demonstrates a subtle lesion deep in the renal parenchyma (arrow).

Sandra Steffens, MD, from the Hannover University Medical School in Germany, who presented the abstract, indicated that despite the fact that “many clinicians have regarded small renal cell cancer as having a benign biologic behavior,” smaller tumors may present with nodal or distant metastases.

This information differs from that of a study presented in February at the 2013 Genitourinary Cancers Symposium by Huang et al, which suggested that surveillance of patients with these small kidney tumors may be a safe alternative to surgery.

Steffens and colleagues examined 2,197 patients with renal cell carcinomas measuring 4 cm or less from six centers in Germany, and measured risk for presenting with nodal disease or distant metastases. Patients were enrolled from 1990 to 2011 and were followed for an average of about 5 years.

There was no association found between increasing tumor diameter and an increased risk for nodal disease or distant metastasis. In addition, no significant difference was found in tumor-associated death rates by tumor size after 5 years of follow-up. Patients with tumors 2 cm or less had a death rate of 6.5%; 2 to 3 cm, 7.6%; and 3 to 4 cm, 8.4%.

Five-year cancer-specific survival rates also did not differ significantly by tumor size, with rates for the three groups of 93.3% (2 cm or less), 92.1% (2–3 cm), and 92.8% (3–4 cm).

Among patients with tumors 4 cm or less, age, metastatic disease, and tumor differentiation were identified as independent prognostic indicators for cancer-specific survival. Those patients with no lymphatic or distant metastasis at the time of diagnosis had a 5-year cancer-specific death rate of 5.8%. Five-year cancer-related death was higher among the 75 patients with nodal or distant involvement at the time of surgery (P < .001).

“These results have significant implications since the rate of patients diagnosed with small renal masses is increasing and nonoperative surveillance protocols are currently being used in patients with small renal tumor,” the researchers wrote in their abstract. “Our data confirm that small RCCs also have an aggressive potential and should be adequately treated.”