High frequency of serum DNA alterations in renal cell carcinoma detected by fluorescent microsatellite analysis

To date there are no reliable serological markers for renal cell carcinoma (RCC). We applied fluorescent microsatellite analysis (MSA) to detect serum DNA alterations in patients with RCC. Fresh tumour, peripheral blood and serum specimens from 60 consecutive patients treated for malignant renal tumours (n= 53 RCC and n= 7 non-RCC) were prospectively collected. After DNA extraction, we performed MSA with a total of 9 markers from the chromosomal regions 3p, 5q, 7p, 7q, 9p, 13q, 17p and 17q to identify tumour specific serum DNA alterations in Group I (n= 53 RCC); 11 additional markers were used in the first 23 RCCs (Group II) in order to increase sensitivity; and 20 healthy controls were investigated with 10 markers. Besides the histomorphological diagnosis the RCCs were genetically stratified according to the "Heidelberg Classification" of renal tumours. Detection of allelic imbalance and loss of heterozygosity (LOH) was carried out on an automated laser sequencer. In Group I we identified serum DNA alterations in 74% (39/53) of cases. When applying 20 markers, the sensitivity was elevated to 87% (20/23) in Group II. Investigating 20 healthy controls with 10 markers, the method rendered 85% specificity. The highest incidence of alterations was detected for chromosomal regions 3p and 5q. The presence of serum DNA alteration was not associated with tumour nuclear grade but exhibited a trend towards advanced stages (p = 0,044). In RCC, the microsatellite analysis has a high sensitivity in the detection of serum DNA alterations when a sufficient number of markers from various chromosomal regions are used. Advanced tumours tend to express serum DNA alterations more frequently.