Clinicopathological characteristics of small renal cell carcinomas.

To clarify the clinicopathological characteristics of small renal cell carcinomas (RCCs) the authors reviewed data for 154 RCC patients treated between January 1980 and September 1992. Of 20 patients with tumours of 3 cm or less in diameter, 12 (60%) had no related symptoms: 6 (30%) were found during routine physical check-ups and 6 (30%) were incidentally detected during examinations for diseases other than RCC. The remaining 8 (40%) patients demonstrated indicative symptoms. Most small tumours showed expansive growth and nuclear atypia was minimal or moderate. In all 20 cases, the lesions of 3 cm or less were confined to the kidney (pT1 to pT2b) and no lymph node metastasis was found. Only one (5%) had a distant metastasis, and venous involvement was also microscopically observed in only one patient (5%). The 5-year survival rates were 95% for patients with tumours of 3 cm or smaller, 74% for those of 3.1 to 5 cm, and 68% for those of greater than 5 cm. These findings revealed small RCC to demonstrate biologically less malignant behaviour. Early detection of such small lesions by ultrasonography should therefore improve the overall survival of patients with RCC.