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Traditionally, if you’d need a cancer biopsy taken, the doctor has to cut and analyze a piece of the actual tumor – but that might change very soon. A new and potentially life-changing method is being tested in labs across the United States.
It’s called liquid biopsy and through recent and very expensive techniques the doctors might only need a blood sample in order to test for cancer DNA in the body. The test is able to find tiny traces of such DNA material in the patient’s blood.
The thing with the blood draw is that it bears benefits for both the patient and the doctor; the patient goes to less trouble than undergoing a traditional biopsy or even a CT scan; and the oncologist can be sure about the efficiency of a treatment and it offers a more stable monitoring tool. If the treatment appears to be failing, oncologists will know to abandon it quicker, sparing the patient of unnecessary side effects and offering the possibility of trying out better alternatives.
Dr. José Baselga, chief doctor and leading medical officer at Memorial Sloan Kettering Cancer Center, said that this technique has the chance of forever changing the follow up procedures on the unresponsive treatments, helping tremendously in the cases of resistance to medication. Down the line, such methods can even be used as a tool in diagnosing cancer in the really early stages.
More proof needed – research underway
However, this strong hope is still in dire need of more proof of efficacy; so far, the test has only been part of smaller studies, analyzed in relation with only a few particular types of cancer (blood, colon and lung cancer).
But even so, the medical world is thrilled. The largest study so far used the test on 126 lymphoma patients – a study conducted by the National Cancer Institute. The results were published in The Lancet Oncology. Apparently, the test was so accurate that it could predict the reappearance of cancer with up to 3 months before CT scans could finally detect them.
The blood test could also specifically identify the patients that were the most prone to therapy resistance. Labs that have not used it yet are also fascinated by the results showed by those which do.
The idea behind the creation of the test is based on a findings dating years ago: it was proved that tiny pieces of fetus DNA could be found in the bloodstreams of their mothers – birthing the idea that tumors – like all growing cells – also shed these little DNA fragments.
But it was not an easy task to find these specific bits of DNA as they were surrounded by a lot of other molecules, especially since they are in circulation only for a few hours before they are stabilized.
Through DNA sequencing, cancer researchers finally found hundreds of mutations – all of which could represent “bar codes” for different types of cancers. That’s how the technology for tracing the cancer DNA was born.
End to the hide-and-seek game with cancer
Traditional assessment methods for how effective a treatment is are rather complicated to apply, as every cancer patient is different and experiences different symptoms – sometimes none.
Even if a treatment is actually helping in the shrinking of a tumor, it might take weeks before that change appears on scans. That happens because scans are designed to show everything surrounding the place where the tumor resides (or used to reside): immune system cells, connective tissue and scars – which sometimes looks like the tumor is still present.
Scars in particular are usually a great setback in finding out the efficiency of a treatment, because they look like a piece of tumor has resisted. According to Dr. Hyman, many tumor biopsies turned out to be only residual lesion, making that invasive procedure unnecessary.
These liquid biopsies also allow step-by-step monitoring, so the oncologists know is the tumor mutates or spreads or become resistant to the medicine. Weekly traditional biopsies are impossible and impractical, while blood tests are usually not a problem.
Early diagnoses through liquid biopsies are still rather tricky. It’s not enough to know that there’s some cancer DNA in the body – you need to know the location and if a course of treatment needs to be developed. There are some cancers that go away on their own and starting treatment might interfere with the body’s processing of the situations.
Two Australian researchers, Dr. Jeanne Tie and Dr. Peter Gibbs, are planning on conducting a study of 450 patients which will be randomly assigned to either have the blood test or not. If cancer DNA is found, those participants will receive chemotherapy.
However, the researchers are concerned about the patients’ reactions when they find they have a very high risk of recurrence, because it usually causes deep anxiety. And the truth is, chemotherapy might not even be helpful. Therefore, the blood test might shed some light, by becoming a clinically useful tumor DNA tracker.
Image Source: ABC News
