Cancer and the Blood; A New Link Between Oncology and Hematology
Gregg Shepard,Medical Oncologist, Tennessee Oncology
In 2011, a partnership between doctors at Harvard University, Mass General hospital in Boston, and the health care company Johnson and Johnson was announced to further develop a new blood test for cancer detection. Cancer and blood have been closely linked since the earliest human awareness of cancer. Ancient Greek and Egyptian physicians knew of the importance of blood and advocated bloodletting for many conditions before anything was known about cancer. The origin of the word “cancer” starts with Hippocrates in about 400 B.C. when he applied the Greek term karkinos, meaning “crab,” to malignant tumors. At that time, bloodletting was the most common medical procedure for any ailment. Bloodletting continued as the most common medical practice worldwide for nearly 2000 years, even though ancient physicians knew that it was not effective as a cancer treatment. The connection was strengthened when acute leukemia, a type of blood cancer in children, was among the first cancers to be cured by chemotherapy in the mid twentieth century. This connection was solidified by the remarkable effect of drugs in use today that target cancer genes to treat chronic leukemia. Most cancer treatments today are still administered directly into the bloodstream by vein, even when the cancer itself has limited blood supply. The connection is coming to the forefront again with the recent news about a test that can capture and analyze a single cancer cell in the bloodstream after it has escaped from a variety of types of cancer. The new test is described as the next generation of circulating tumor cell (CTC) technology in a Jan. 3 press release.
In the recently announced research version of the test, a microchip is coated with antibody proteins. A blood sample then flows over the chip, and the proteins trap single cancer cells. According to the researchers, a single cancer cell can be isolated from over a billion normal blood cells. A single drop of blood contains about 1 million normal cells, so this test might be able to detect a single cancer cell in one standard blood test tube. The cells can then be analyzed in a variety of ways similar to the analysis of cancer cells from traditional biopsy procedures. This might include analysis of specific genes and other cancer cell features in an effort to provide personalized cancer treatment.
The current generation of CTC testing, called CellSearch, is able to count the number of cancer cells in the bloodstream with similar sentitivity, but is not able to analyze details about the genes or other features of those cells. CellSearch is approved for monitoring certain types of advanced cancer but has not been shown to detect or analyze early forms of cancer. The new test may have the ability to detect cancers earlier and analyze them in detail, potentially reducing the need for more invasive and risky biopsy procedures. Even more exciting is the idea that a blood test could detect cancer very early in people at risk. The promise of early cancer detection from a blood test led a major biotechnology company to invest in the technology, which led to stories on CNN, Today, and NBC Nightly news. Most cancers can be cured if detected very early, but effective early detection is currently limited to only a few types of cancer. Early detection is the principle behind regular mammograms for healthy woman and screening colonoscopies for all people over age 50. Like most people, I don’t look forward to the discomfort and inconvenience of a colonoscopy even though I understand its importance, but getting a blood test at a doctor visit is almost routine. There is nothing routine about a cancer diagnosis, but this effort to improve cancer treatment using a blood test might be a big step in the right direction. For now, patients with cancer can find out if the test to detect cancer cells in the blood is right for them.
You can read the new story and watch video from CNN here: http://www.cnn.com/2011/HEALTH/01/03/cancer.test/ and from Today here: http://today.msnbc.msn.com/id/40881967/ns/health-cancer/40888824
You can read the press release from Johnson and Johnson here: http://www.jnj.com/connect/news/product/veridex-llc-announces-collaboration-to-develop-next-generation-circulating-tumor-cell-technology-with-massachusetts-general-hospital
Information about the CellSearch circulating tumor cell test is here: http://www.veridex.com/CellSearch/CellSearchHCP.aspx