AB255. A study on the clonal origination of multifocal clear cell renal cell carcinoma

Background: Nephron sparing surgery has become a prior treatment for the early stage renal cell carcinoma (RCC). Multifocal RCC is an important reason that causes the recurrence. In this study, we discovered the origination of multifocal RCCs, aimed at providing a theoretical foundation for clinical treatment. Methods: Sixty-five tumors from 27 multifocal RCC patients were collected and microscopic incised. The genome DNA was extracted. The loss of heterozygosity (LOH) of polymorphous micro satellites on 3p25 (D3S1317, D3S1038, D3S1597), 3p14 (D3S1300, D3S1234, D3S1540), 7q31 (D7S522), 8q21 (D8S261), 9q21 (D9S171), and 17p13 (TP53) genes was detected. The X chromosome inactivation was detected on the female cases. The results were compared with normal renal tissue. Results: Twenty-five of 27 cases (93%) have LOH on at least one micro satellite. The LOH rates were: D3S1317 29%, D3S1038 25%, D3S1597 26%, D3S1300 17%, D3S1234 20%, D3S1540 31%, D7S522 29%, D8S261 22%, D9S171 23%, TP53 46%. Eighteen cases (66.7%) showed a common LOH type. In the 10 female cases whom were found non-random X chromosome inactivation, two (2/10, 20%) patients’ multifocal foci appeared different X chromosome inactivation types from original ones, the other 8 patients’ multifocal foci and original ones showed the same X chromosome inactivation type. Conclusions: In most cases, multifocal RCC foci shares a common clonal origin. But in minority cases, multifocal RCC foci are independently originated.