[Detection of circulating epithelial cells in prostate cancer]

The prostate cancer, which is the second cause of cancer, is in constant increase. This is linked to the ageing of population which is in fact a medical and socioeconomic problem. The curative therapeutic attitude of the localized prostate cancer are either wath-full waiting, radiotherapy or radical prostatectomy. With the actual clinical and radiological techniques of stadification, 40% of the localized prostate cancer are extraglandular on the prostatectomy specimen. Recently, the RT-PCR seems to be a more specific and sensitive technique to detect circulating epithelial cells compared to others techniques (immunocytochemistry or flow cytometry). The detection of these circulating cells, would be correlated to the anatomopathologic stage. The use of RT-PCR as a tool of molecular stadification should be considered.

This study evaluates and compares with in vitro pattern, the different techniques of separation (ficoll, gradient, osmotic shock) and detection (immunocytochemistry, flow cytometry and RT-PCR).

The ficoll gradient is the best technique of cellular separation preserving cellular morphology and RNA. The detection level are 1 cell LnCap per 40,000 lymphocytes cell by immunocytochemistry, 1/1000 by flow cytometry, 1/10,000 to 1/1,000,000 by RT-PCR.

The RT-PCR with its low detection level and its high specificity, is the best technique of detection of epithelial circulating cells in localized stage. The advantage of immunocytochemistry is its simplicity. Its use for circulating cells caracterization can be considered for metastatic stage.