Researchers in labs across the country are now testing a new way of performing biopsies on cancer patients that has the potential to truly transform the way physicians screen for cancer. The new test, called the liquid biopsy, is a new blood test that shows promise in detecting snippets of cancer DNA in a patient's blood.
In a typical cancer biopsy, a surgeon must cut out a piece of the patient's tumor, which can potentially be invasive and hard on patients already weakened by their disease. The hope of the new liquid biopsy is that the simply blood draw can be as effective and far less onerous for patients than a traditional surgical biopsy or CT scan. Researchers also hope that it will enable oncologists to more quickly determine whether or not a treatment is working and, if it is, to continue monitoring the treatment in case the cancer develops resistance. If oncologists can determine that a treatment is failing more easily, they can quickly alter the treatment sparing patients many grueling side effects and improving treatment options for the patients.
"This could change forever the way we follow up not only response to treatments but also the emergence of resistance, and down the line could even be used for really early diagnosis," said Dr. José Baselga, physician-in-chief and chief medical officer at Memorial Sloan Kettering Cancer Center.
Researchers, however, caution that more evaluation is needed to be certain of the test's accuracy and reliability. So far, there have only been small studies on specific cancers, including lung, colon and blood cancer. But early results from the test have been encouraging.
Oncologists who are not using the new test say they are looking on with fascination. "Our lab doesn't do it, but we are very interested," said Dr. Levi Garraway of the Dana-Farber Cancer Institute. "It's exciting. It's a top priority."
Patients often have scans to determine if treatment is working, but it can take weeks or even months for tumors to look smaller on a scan fooling doctors that there is still a tumor present when, in fact, it is gone.
"When you are treating a patient - and we see this many times - your treatment is quite effective but there is some residual lesion on a scan," Dr. David Hyman, the oncologist at Sloan Kettering, said. "You take the patient to surgery for a biopsy, and all you see is scar tissue. There is no visible cancer there."
The blood tests allow for frequent monitoring of tumors as they shrink, spread or mutate and develop resistance to treatment. "I cannot do a weekly liver biopsy and see how things are going," Dr. Baselga says. "But I can do a blood test every week."
Another possible application is the early diagnosis of cancer, but this application is a bit trickier. If a blood test shows cancer DNA, what exactly would that mean? Where is the tumor, what type is it and will this early detection even help? Some cancers stop growing or even go away on their own and with others, the outcome is just as good even if it is found later.
The other concern is patients will be told their blood tests as many researchers wonder how some will react.
"If you find DNA and tell the patient there is a very high risk of recurrence, that creates a lot of anxiety," Dr. Gibbs says. "And we are not sure chemotherapy will be helpful."
The blood test, they hope, will answer that question.
