Objectives: The indication for elective nephron-sparing surgery (NSS) in renal cell carcinoma (RCC) is still controversial. The presented study was performed to determine limitations for NSS regarding to multifocality and to characterize the biological importance of these small tumor lesions.
Methods: In 372 patients who underwent radical nephrectomy for RCC consecutively, nephrectomy specimens were investigated by using 3-mm parenchyma sections regarding to local tumor spread and multifocality. To characterize multifocal tumors, we performed cytogenetic and molecular genetic investigations.
Results: Serial sections of 372 nephrectomy specimens revealed a total of 92 multifocal tumors in 61 specimens (16.4%). The correlation between tumor size and multifocality is shown as follows: tumor diameter 1-20 mm: 12.5%; 21-30 mm: 23.4%; 31-40 mm: 10.2%; >40 mm: 16.7%. The mean diameter of the multifocal tumors was 8.8x9.1x6.1 mm and the mean distance to the primary tumor was 26.4 mm (5-84 mm). Using cytogenetic and molecular genetic analysis, in nearly one third of all cases a concordance of chromosomal aberrations in primary and secondary tumors was found.
Conclusions: Multifocality of renal cell carcinoma occurs independently from primary tumor size. The evidence of structural and/or numeric aberrations, found in additional tumor foci, obviously is an argument for their malignant potential. This findings have to be considered in preparation of nephron-sparing surgery for patients with renal cell carcinoma.