Low local metastatic rate may widen indication of nephron-sparing surgery for renal cell carcinoma.

To explore the rationale for renal-sparing surgery as an alternative method to radical nephrectomy in the treatment of renal cell carcinoma (RCC), we analyzed clinical data from 94 patients diagnosed as having RCC. They were divided into 3 groups based on the maximum diameter of their tumor specimens. Group A had tumors size ranging from 0 to 4 cm, group B had tumors size ranging from 4 to 7 cm, and group C had tumors size greater than 7 cm. Tissue samples (5 cm) were taken from the upper pole side, lower pole side, and renal pelvic side of the tumor pseudocapsule; if the tumor was located on 1 pole of the kidney, samples were collected from 2 directions. The specimens were then embedded in paraffin and cut serially at segments 0 to 1, 1 to 3, and 3 to 5 cm. Staining with hematoxylin and eosin, anti-pancytokeratin, and vimentin was performed to determine tumor type and tumor infiltration. From the 94 patients analyzed, 2 patients in group A had RCC metastasis within 1 cm of tissue around the pseudocapsule, and 4 patients in groups B and C had lymph node metastasis without metastasis in the tissue 1 cm outside the pseudocapsule in all 3 directions described. There was no statistical significant difference found between the incidence of local metastasis of the various tumor sizes, suggesting that local metastasis of RCC is not associated with the size of the tumor. Based on the observation that incidences of local metastasis were low in early-stage RCC, we came to the conclusion that pseudocapsule of RCC tumor might have growth-limiting effect on the tumor enclosed. It is theoretically a safer and better surgical option for patients with RCC with a smaller size of tumor and indications for radical nephrectomy to undergo renal-sparing surgery with an excision margin of 1 cm of normal tissue around the pseudocapsule of the tumor.