Chromosomal gains and losses detected by comparative genomic hybridization and proliferation activity in renal cell carcinoma.

Abstract

The number of DNA losses found using comparative genomic hybridization (CGH) and the proliferation index MIB-1 have been shown to be prognostic factors in renal cell carcinoma (RCC). We evaluated the associations of these two factors with each other and with histopathology and clinical outcome. In this prospective study, specimens from 20 primary RCCs were investigated using CGH and MIB-1 assay. The associations of the commonest chromosomal aberrations with histopathology, stage and the clinical outcome of the disease were evaluated. CGH detected genetic aberrations in all tumours. Losses of genetic material (85%) were more common than gains (65%). Most common was loss in the short arm of chromosome 3, which was found in 70% of the tumours. Other frequent changes (20%) were losses of 4q, 13q, 18 and Xp, as well as gains of 5q, 7p, 7q (25%) and chromosome 12. The number of deleted chromosomal areas varied from none to six. The MIB-1 index varied from 0 to 39 (median 4.0). The total number of chromosomal aberrations or deletions showed no association with MIB-1 index or nuclear grade. Most grade 1 and 2 tumours showed a low MIB-1 index. All nuclear grade 4 tumours progressed and were associated with short survival. CGH gives an overview of DNA changes in RCC and helps to locate targets for more precise genetic evaluation. CGH findings are also helpful for classifying tumours. In this study, genetic aberrations in primary RCCs were not associated with histopathology, proliferation or clinical outcome, which suggests that CGH does not necessarily give any additional information on the prognosis of the disease. MIB-1 index and TNM stage were associated with survival.