Metastatic disease rarely occurs in patients with renal tumors less than 3 cm in diameter, data show.

The finding suggests that nephrectomy might be avoidable in patients who have such small tumors, an important consideration if these patients have comorbidities, said lead investigator R. Houston Thompson, MD, a urology fellow at Memorial Sloan-Kettering Cancer Center in New York City.

He and his colleagues studied 2,691 patients treated surgically for a sporadic renal cortical tumor. Of these patients, 162 presented with metastatic renal cell carcinoma (RCC). Only one of 781 patients with a tumor less than 3 cm in diameter had M1 metastases at presentation. Each 1-cm increase in tumor diameter was associated with a significant 25% increase in the risk of metastasis and a 24% increase in the risk of death, Dr. Thompson reported.

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During a mean follow-up of 2.8 years, metastases developed in 171 of the 2,367 subjects who did not present with metastatic disease. Of the 2,367 subjects, 720 had an RCC tumor less than 3 cm in diameter, de novo metastases developed in only one of these patients during follow-up.