Abstract
The present study was aimed to develop a method to detect cancer cells in venous blood of cancer patients, either for screening for following-up. Heparinized venous whole blood of about 10 milliliters from the subjects were processed for red blood cell lysis and white blood cell depletion. The cells remained were cryo-fixed and stained using commercially available reagents claimed to give a good morphology of the fixed cells that could be stored for many months. Blood samples were collected from 25 colon cancer patients and 12 subjects who were negative for colon cancer screened by colonoscopy. Early in the study, blood samples from 2 breast cancer patients, 5 hepatocellular carcinoma patients, 1 cholangiocarcinoma patient, 1 lung cancer patient and 1 osteosarcoma patient were also collected. Antibodies against vimentin, cytokeratin, CD45, CDX2, CD31 and CD34 were used. Due to a technical problem on red blood cell lysis and staining temperature, a few weeks were spent to solve it and later cells could be fixed and stained at low temperature. Other optimizations included low temperature handling steps and concentrations of antibodies. The immuno-stained cells appeared mostly to be white blood cells of good morphology. A pathologist had investigated the stained samples and found that there were only 2 cases out of 25 colon cancer patients that seemed to have some abnormal/cancer cells. These were larger and their neclei were also bigger than the nearby white blood cells. They were especially positive for CK 20 and CDX2, the latter being reported to be specific for adenocarcinoma. However, the size of many abnormally stained cells found in many cases was similar to white blood cells, it may be concluded that in this present study abnormal cells could be found in blood samples of colon cancer patients but perhaps with a very low sensitivity. Also owing to quite a high cost of reagents for cell isolation and low temperature processing, this method at the moment could not be used as a routine colon cancer screening.
