Small Renal Cell Carcinomas: Correlation of Size with Tumor Stage, Nuclear Grade, and Histologic Subtype

OBJECTIVE. Our goal was to correlate the size of renal cell carcinoma with tumor stage, nuclear grade, and histologic subtype in patients treated using partial or radical nephrectomy. MATERIALS AND METHODS. We retrospectively reviewed 213 consecutive renal cell carcinomas resected at our institution from 1995 through 1999. Three groups of lesions stratified by size (≤ 3 cm, > 3-5 cm, > 5 cm) were compared with regard to pathologic findings. Statistical significance was assessed using Fisher's exact test. RESULTS. Of 50 lesions 3 cm or smaller, 19 (38%) had extension outside the renal capsule (T3 or T4) and 14 (28%) were a high nuclear grade (Fuhrman grade 3 or 4). Lesions 3 cm or smaller and those greater than 3 cm to 5 cm did not differ statistically with regard to T stage or nuclear grade. Lesions larger than 5 cm showed a statistically higher T stage (p < 0.001) and nuclear grade (p = 0.001) than the other smaller lesions. More non-clear cell tumors were found in the two groups of smaller lesions (p = 0.105) but without statistical significance. The majority (58%) of the tumors were asymptomatic and had been detected incidentally on cross-sectional imaging. Lesions larger than 5 cm were significantly more likely to be symptomatic (p < 0.001). Seventy-nine percent of the tumors 3 cm or smaller were incidental, and these lesions did not differ significantly from the symptomatic lesions with regard to stage, grade, or histology. CONCLUSION. In our study population, renal cell carcinomas up to 3 cm, including asymptomatic lesions, showed a significant incidence of high nuclear grade and tumor extension beyond the renal capsule; these findings support aggressive management of small lesions. Symptomatic status was not an adequate discriminator to guide management. A longitudinal study is necessary to further evaluate the efficacy of current patterns of therapy.