Simple Blood Test to Detect Cancer? Not So Fast

Experts question whether blood test could revolutionize cancer treatment.

January 3, 2011, 4:50 PM

Jan. 3, 2011— -- Researchers from Massachusetts General Hospital and health giant Johnson & Johnson are combining efforts to streamline a simple blood test that may be able to identify cancer cells in the blood stream of patients already diagnosed with a specific type of cancer.

But many experts question what place, if any, this test will have in the world of cancer prevention, early detection or even treatment.

The partnership is part of a nearly $30 million endeavor funded by Johnson & Johnson company Veridex and the advocacy group Stand Up to Cancer to develop and refine technology that will be able to accurately and quickly detect and analyze circulating tumor cells, the company said Monday.

Circulating tumor cells are a rare form of free-flowing cancer cells detached from the smallest of tumors and can be found at extremely low levels in the blood stream.

"For every one tumor cell in the blood there's over a billion normal blood cells in the circulation. So that's the big challenge for developing a test that can pull out one in a billion cells," said Dr. Daniel Haber, director of the cancer center at Massachusetts General Hospital in Boston.

CTC technology, approved by the Food and Drug Administration in 2004, is widely used in cancer centers to monitor a patient's response to treatment. But researchers now hope to expand its use to create a faster automated version that will analyze genetic components of a tumor and ultimately guide oncologists to personalize cancer treatments for patients.

"Harnessing the information contained in these cells in an in vitro clinical setting could enable tools to help select treatment and monitor how patients are responding," said Robert McCormack, head of technology innovation and strategy at Veridex.

Some cancer experts agreed the technology may be able to track some patients' cancer progression.

"It can help oncologists determine how well the drugs are working to kill cancer cells and it potentially could tell if the tumor returns at a later time," said Dr. Sarah Blair, associate professor of surgery in the division of surgical oncology at University of California San Diego.

However, previous research suggests that monitoring cells during treatment does not necessarily improve a patient's outcome. And many experts said not all indications of cancer cells in the body warrant treatment.

"Having the cells in the bloodstream does not necessarily mean that the cancer will spread and kill you," said Susan Love, president and medical director of the Dr. Susan Love Research Foundation, a breast cancer support and advocacy organization. "Just because you find them does not mean you know what to do with the information."

In some cases, our bodies may be able to fight off cancer cells without treatments such as surgery or chemotherapy, she said.

"We all have cancer cells in our body that are dormant," Love said. "We need to be careful not to over react to the presence of cancer cells when the treatment may actually be worse than the cure."

While in other cases, circulating tumor cells in the bloodstream that do signal cancer might mean the cancer may have already metastasized, she said.

Unlike other cancer screening tests that identify proteins released by cancer cells such as prostate-specific antigen for early prostate cancer detection, or rely on radiology studies such as mammography for early detection of breast cancer, CTC technology works when researchers look for actual tumor cells in the blood from a patient who is already diagnosed with a specific type of cancer.

According to Haber, for those already diagnosed with cancer, the test may be able to identify the cells' specific DNA, and doctors can subsequently tailor more effective treatments.

"Every patient has a different kind of cancer, every cancer has a different set of mutations and the better we get at treating cancer, the more we use specific drugs or smart drugs that are targeted against specific genetic abnormalities in the cancer," Haber said. "It's a way of understanding the cancer in real time and targeting therapy against the specific cancer at a particular moment in time."

And while researchers like Haber embarking on the collaboration hope the test will monitor cancer progression in cancer patients and ultimately personalize a cancer patient's treatment, many experts say it's still too early to tell.

"What we don't need are more tests that measure this or measure that," Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society wrote in his blog. "What we desperately need are tests that make a difference in the lives of our patients."

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