Nephron-sparing surgery for renal cell carcinoma--is tumor size a suitable parameter for indication?

Because patients with small renal cell carcinomas (RCC) are being treated by nephron-sparing surgery with increased frequency, a generally accepted parameter giving additional information as to which kind of tumor is suitable for this treatment is urgently required.

In a retrospective analysis of 245 patients who underwent radical nephrectomy for RCC, we investigated whether tumor size could provide the necessary information. We analyzed the association of tumor size with pTNM classification, grade, and the findings of the flow cytometric analysis of the DNA content analyzing the DNA index (DI).

Stage pT1 was found in 23 patients (9.4%), pT2 in 100 (40.8%), pT3 in 109 (44.5%), and pT4 in 13 patients (5.3%). Grade 1 was found in 87 patients (35.5%), grade 2 in 120 (49.0%), and grade 3 in 38 patients (15.5%). A low DI was found in 71%, a moderately increased DI in 20%, and a high DI in 9%. Lymph node metastases were detected in 14% and -distant metastases in 22%. Closer examination of the tumors less than 2.5 cm (n = 23) revealed a significantly lower incidence (P <0.001) of infiltration of the renal capsule (n = 0) than in the rest of the group. Positive lymph nodes or distant metastases could not be found in this subgroup. A multifocal appearance of RCC was detected in only 2 (8.7%) of the 23 patients; it was detected in 67 (30.2%) of the 222 patients in the rest of the group. None of the 23 patients had grade 3 tumors (P <0.05). Fifty-two percent of the tumors were grade 1 and 48% grade 2. None of the 23 had a high DI; a moderately increased DI was found in 1 patient and a low DI in 22 of the 23 patients. Detailed examination of the tumors between 2.5 and 4 cm (n = 29) revealed an infiltration of the renal capsule in 11 (38%); lymph node metastases were found in 2 (6.9%) and metastases in 4 (13.8%). A multifocal appearance was found in 4 (13.9%) of the 29 patients; grade 3 tumors were detected in 3 (10.3%) of 29 patients, grade 2 tumors in 12 (41.4%), and grade 1 tumors in 14 (48.3%). In this subgroup, a high DI was found in 14% (not significant). The examination of tumors larger than 4 cm in size revealed worse results in the pTNM classification, grade, and flow cytometric results.

Only tumors smaller than 2.5 cm should be considered suitable for nephron-sparing surgery in patients eligible for elective surgery. In patients in whom nephron-sparing surgery is imperative, even tumors between 2.5 and 4 cm appear to be suitable. In patients requiring extensive resection, however, the risk of local recurrence seems to be higher because of the higher incidence of multifocality.