MONDAY, Jan. 3 (HealthDay News) -- A collaboration of U.S. scientists and private companies are looking into a test that could find even one stray cancer cell among the billions of cells that circulate in the human bloodstream.
The hope is that one day such a test, given soon after a treatment is started, could indicate whether the therapy is working or not. It might even indicate beforehand which treatment would be most effective.
The test relies on circulating tumor cells (CTCs) -- cancer cells that have detached from the main tumor and are traveling to other parts of the body.
In 2007, researchers at Massachusetts General Hospital, developed a "microfluidic chip," called CellSearch, which could count the number of stray cancer cells, but that test didn't allow scientists to trap whole cells and analyze them.
But on Monday, Mass General announced an agreement with Veridex LLC, part of Johnson & Johnson, to study a newer version of the test. According to the Associated Press, the updated test requires only a couple of teaspoons of blood.
The microchip is dotted with tens of thousands of tiny posts covered with antibodies designed to stick to tumor cells. As blood passes over the chip, tumor cells separate from the pack and adhere to the posts.
Scientists are wagering that this type of test, if successful, might also detect cancer early in its course, predict the odds for a recurrence, and assess a patient's general prognosis.
"There has been speculation that these [stray] cells are the ones that are responsible for the spreading of the disease," noted one expert, Dr. Massimo Cristofanilli, professor and chairman of medical oncology at Fox Chase Cancer Center in Philadelphia. "Simple enumeration tells us that this patient has a worse prognosis . . . Now the question is, what other information we can gather, if we are able to capture these cells? For example, could we do gene analysis profiling and can we get information for the best treatment?"
As it stands today, biopsy -- an invasive and sometimes even hazardous procedure -- is one of the few ways doctors can get key information about a cancer's size and characteristics.
"Many people consider [the new blood test to be] a 'liquid biopsy,' so that eventually we can access cancer cells that are representative of the tumor without performing an invasive biopsy," said Cristofanilli, who is not involved in developing the test.
Experts stressed that the new type of test, if it ever arises, may still be years away, and researchers still aren't sure what these circulating tumor cells (CTCs) actually mean.
"They may be able to detect small amounts of cancer cells but we don't know the significance of that. We may be detecting things that don't have clinical significance," explained Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge.
And as Cristofanilli pointed out, these plans so far are "only for research. The test is not available for clinical use." According to the AP, four major cancer centers -- Mass General, Memorial Sloan-Kettering Cancer Center in New York City, the University of Texas' M.D. Anderson Cancer Center in Houston, and the Dana-Farber Cancer Institute in Boston -- will begin studies using the new test this year.
The test would need to be developed "along with the process of new drug development and new targeted therapies so we can better use the information with a clinical purpose," Cristofanilli added.
There's more on cancer's spread at the U.S. National Cancer Institute.
SOURCES: Jay Brooks, M.D., chairman of hematology/oncology, Ochsner Health System, Baton Rouge, Louisiana; Massimo Cristofanilli, M.D., professor and chairman, department of medical oncology, Fox Chase Cancer Center, Philadelphia;
Jan 3, 2011 Associated Press
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