The detection of circulating tumour cells (CTCs) from peripheral blood of cancer patients can be carried out by real-time PCR approaches using different gene expression levels of tumour cells and surrounding blood cells.

Potential marker genes were first analyzed in a model system and then applied to 20 blood samples of adjuvant breast cancer patients and gene expression levels were correlated to tumour characteristics.

The mean of gene expression levels was found elevated for the four genes analyzed in the adjuvant breast cancer patient group in comparison to the samples of the group of healthy donors, but no correlation between gene expression and tumour characteristics could be detected as being statistically significant.

The results demonstrated, that the employed methodology is functional, but has to be refined by certain approaches like simultaneously running a state-of-the-art system of CTC-detection comparing the results, and by an enlargement of patient collective and number of marker genes.