Winship at Emory’s Dr. Suresh Ramalingam explains the test and what it means for cancer detection and treatment.
You may have heard in news headlines this week about the ability to detect a single cancer cell among billions of healthy cells. This may be possible via a new blood test (under development) that may someday help detect cancer earlier.
For tumors located in organs such as the lung, prostate, colon and breast, access to tumor tissue is only possible with a biopsy. This requires an invasive procedure, which in certain situations involves surgical intervention. It has been known for sometime that tumors shed their cancer cells that can be found in the circulating blood stream. However, the tumor cells are a significant minority in number compared to normal blood cells. Identifying the tumor cells among billions of normal cells has been a major challenge. Currently, it is possible with sophisticated techniques to identify such cells and count them. The number of circulating tumor cells has been linked to survival outcomes in some studies. Now researchers are trying to not only count, but collect these tumor cells and then conduct molecular testing.
Such an advance would have tremendous implications for cancer research and treatment. First of all, it may not be necessary to obtain tumor biopsies if adequate number of cells can be identified in the peripheral blood. It will be possible then, to administer this test during the course of a patient’s treatment to learn how a tumor is changing, because they do change as treatment progresses. It would also be possible to diagnose cancer early as part of screening strategies for patients at risk for developing certain cancers.
So how does this test work and what does it do? The test uses a microchip resembling a lab slide covered in 78,000 tiny posts. Those posts are coated with antibodies that attract and bind to tumor cells like glue. A patient’s blood sample, about a teaspoon full, is forced across the chip. The cancer cells stick, and a stain makes them glow so researchers can capture them for study.
For patients, care-givers and researchers this is very exciting news. However, this technology is just entering the early stages of testing and will have to go through several studies before it can be applied in routine practice. A number of important research questions will still have to be answered regarding the utility of circulating tumor cells, even if the test proves to be successful.
It is important to emphasize that while the new technology is exciting, it is possibly years away from practical application. If you have questions on this new blood test, please leave them in the comments below.