Circulating tumor cells (CTCs) are epithelial cells with nucleus circulating in the blood of cancer patients. Levels of abundance of these marker cells in the circulating blood of cancer patients undergoing treatment may indicate the severity and progression of the cancer and overall survival. These cells are extremely rare in numbers in the blood and identifying them and harvesting them has been a challenge. This is a new field of research, and there is no real understanding of these cells. We still do not know the origin of these cells, how to accurately identify them, harvest them, and how to make use of them once harvested. There are a number of companies and research labs are addressing this issue and in recent years have introduced a number of products into the market.
One of the products available in the market is called CellSearch from Veridex. This company develops in vitro diagnostic oncology products, which helps in the early detection and allow doctors prescribe a personalized approach to teat their patients.
CellSearch is an in vitro diagnostic test kit to capture, and quantitate circulating tumor cells in the patient’s blood. It is currently used for the detection of circulating tumor cells from patients with metastatic breast cancer, prostate and colorectal cancer. Doctors use this test to measure the efficacy of the treatment, and monitor the progress of their patients. Although very little is known about these cells, they do sometimes correlate with the patient out come.
It has been reported that the circulating tumor cells vary within the same blood sample, making one wonder if it is a true representation of the evolving tumor?. If so one might be able to characterize them and recommended a personalized targeted therapy to the patient. With the type of correlation seen between the circuiting tumor cells and degree of metastasis, can circulating tumor cells be used as a liquid biopsy?.
ISOLATION AND ENUMERATION
There are different techniques available today to capture the circulating Tumor cells. CellSearch is one of them other methods includes, MagSweeper- a magnetic based cell enriching system yielding a highly pure CTCs which can be analyzed. It will be interesting to compare side by side different population od CTCs purified from the same pool of blood using different methods, study the variability if any and try to understand what we can learn from each population. Some capture the CTCs and stain them for molecular markers and study them and quantitate them. For such purposes one of the products from Pioneer Scientific (www.pioneerscientific.com) is a multiwell plate with grids and cell culture petri dish with grid pattern. These tools will allow keeping track of the CTCs in the enriched population of cells after selective staining. This culture dish could be very valuable for quick quantitation and enumeration of the circulating tumor cells.
Whatever the techniques used to capture, quantitate, and analyze the circulating tumor cells from the patient, it provides a unique window into the patients evolving blood stream during the therapy, and indicate the outcome of the disease progress. With continued research we will have a through understanding of these valuable cells and can be used as a true measure to approach disease management as personalized medicine.