Blood tests have long told us a lot about what’s going on in our bodies—from whether we have certain conditions like diabetes to whether our organs, like our heart and liver, are functioning as they should.
But imagine if a small sample of your blood could screen for cancer long before you ever show any symptoms. And not just that, the test could also give you clues on how to specifically treat that cancer. No, this isn’t science fiction. It’s a diagnostic test, sometimes called a liquid biopsy, that evaluates circulating tumor DNA (ctDNA). A ctDNA test can look for cancerous genetic materials in your blood and is currently the main way doctors diagnose most types of cancer.
Although tissue biopsies can be relatively easy to collect if located in the mouth, skin or breast, this isn’t the case for tumors that lie deep inside the body, such as in the liver, lung or colon. In these cases, taking a tissue biopsy can be difficult, painful or even impossible.
An alternative to tissue biopsy that allows for less invasive, less painful and faster testing is a liquid biopsy.
“During a liquid biopsy, a small blood sample is taken from you and spun down to get plasma, the liquid portion of blood,” said Michael Choti, MD, a surgical oncologist and division chief of surgery at Banner MD Anderson Cancer Center at Banner Gateway Medical Center. “The plasma is then analyzed for fragments of mutated ctDNA in the bloodstream.”
Much of the early research on liquid biopsies has been on lung, colorectal, breast and prostate cancers but the technology could be a game-changer in the way we understand and treat all types of cancers.
“ctDNA testing can give fast, safe and non-invasive access to draw out and identify mutations in the bloodstream,” Dr. Choti said. “This technology is just emerging in cancer management, but much like the innovation of CT scans or X-rays in the 1950s, I think liquid biopsies have the potential to transform the way we diagnose, treat and manage cancer forever.”
What you should know about ctDNA testing
If you or a loved one have recently been diagnosed with cancer or have just completed treatment, here are some important things to know about this emerging technology.
Early cancer detection
While imaging tests like CT, MRI and PET scans are used to identify tumors that have already formed, ctDNA testing may be much more sensitive.
“These tests can identify minute mutations in the blood, even before a cancer is visible on a scan or someone begins experiencing symptoms,” Dr. Choti said. “Studies are underway to determine the role of ctDNA testing as a diagnostic screening tool. For example, in colorectal cancer, this new technology may eliminate the need for routine screening colonoscopies in the future.”
Providing a story versus of snapshot of the cancer
While tissue biopsy is still a standard diagnostic tool for identifying and treating cancer, it only tells half the story. Liquid biopsy could offer a faster, less painful alternative that can be repeated multiple times, enabling doctors to get a clearer picture of the biology of the cancer.
“When you do a tissue biopsy of a cancer, it’s only a snapshot of that cancer at one point in time and may only sample a small fraction of the whole tumor,” Dr. Choti said. “Whereas with a ctDNA test, you can get a richer story on what is going on and see changes over time—like is the cancer gaining resistance, growing or responding to treatment?”
Monitoring cancer remission
Even if you’ve recently completed treatment for cancer, such as a surgical removal, some cancer cells can still be left behind in your blood. These tiny bits are called minimal residual disease (MRD).
To determine if you are truly in remission, a ctDNA test could be used to determine if you have some amount of MRD still in your body. In such cases, therapy can be started sooner, improving the chances for a cure. A negative ctDNA test after surgery may be able to reduce the number of patients receiving unnecessary chemotherapy in the future.
Guiding individualized treatment
A liquid biopsy may help determine how you are responding to certain treatment therapies and could even direct certain targeted therapies.
“If a patient’s cancer isn’t responding to chemotherapy, we will be able to know pretty quickly with a ctDNA test rather than waiting months to see changes on a scan,” Dr. Choti. “This enables us to track a therapy’s effectiveness or identify new mutations that develop. We can basically monitor cancer cell resistance and create more personalized treatment therapies.”
Designing clinical trials
Studies have shown that the use of ctDNA clinical trials are enabling researchers to return results more quickly and efficiently, therefore accelerating drug development and more targeted therapies.
“With ctDNA testing, it will enable us to design clinical trials that involve fewer patients and a quicker turnaround time to determine if a potential drug is effective or not,” Dr. Choti said. “This will help with the discovery of new drugs more quickly and won’t subject patients to therapies that are no longer of value.”
Although the technology is still new, clinical trials are opening doors for researchers like Dr. Choti to find the best way to utilize this diagnostic tool in the treatment of their patients.
“We’re uncovering so many treatment opportunities and a richer understanding about cancer and patient than we’ve ever been able to before,” he said.
Talk to your health care provider
If you’ve recently been diagnosed with cancer, talk to your health care provider to determine if you’d be a candidate for a liquid biopsy. To find a Banner MD Anderson Cancer Center specialist near you, visit bannerhealth.com.