Cancer detection and treatment may be on the cusp of a paradigm shift thanks to the rise of liquid biopsies. These minimally invasive tests analyze circulating tumor DNA (ctDNA) – fragments of DNA shed by cancer cells into body fluids like blood – to detect and monitor disease and guide treatment in real time.
“This is pretty revolutionary testing, which has only been commercially available to oncologists for four or five years,” said Dr. Simon Vinarsky, a hematologist/oncologist at Cleveland Clinic Indian River Hospital.
“While we’ve always had the technology to detect circulating cancer cells in hematological malignancies such as leukemia and lymphomas, solid tumors like colon, breast, lung and pancreatic cancers have been much more challenging. But with evolving technology, we now can detect circulating DNA from solid tumors, which makes a tremendous difference in our ability to offer our patients cutting-edge personalized medicine tailored to their needs.”
Circulating tumor DNA refers to tiny fragments of cancer-driven DNA found in the bloodstream.
According to BioMed Central, liquid biopsies are safer, more repeatable, and capture a broader picture of tumor biology across multiple sites, compared to other tests. Unlike tissue biopsies – which require surgical procedures – they require only a simple blood draw.
“It’s a simple blood test drawn from your arm and sent to a lab that can detect circulating cancer cells,” Dr. Vinarsky explained.
This innovative testing isn’t recommended yet for the general population for the purposes of cancer screening. It is used for patients with a high-risk cancer history, who are being closely monitored or actively treated.
Once collected, plasma samples are analyzed using sophisticated tools capable of detecting rare mutations with high sensitivity, even when ctDNA makes up just a tiny fraction of total cell-free DNA, pinpointing a single rogue DNA molecule among 10,000 normal ones.
The evolving tests can identify cancer recurrence or residual disease months or even years before imaging methods detect them. For example, a new breast cancer blood test detected recurrence up to three and a half years before scans, as shown in a trial monitoring 1,800 mutations that was presented at a recent major oncology conference.
Since ctDNA reflects DNA from the entire tumor, including metastases, it can offer a more comprehensive genomic profile than localized tissue biopsies.
Liquid biopsies cannot pinpoint tumor location, so follow-up imaging or tissue biopsies are still necessary if ctDNA signals are detected, but ctDNA testing can help oncologists track how patients respond to therapies.
Dr. Vinarsky cited several examples of patients with high-risk colon cancer, breast cancer or lung cancer where this test makes a big difference in intensity and duration of systemic treatment.
In turn, faster, more accurate treatment can make a huge difference in the intensity of side effects and a person’s quality of life.
“We can use this testing to select patients who absolutely need an aggressive systemic treatment if they have evidence of circulating tumor DNA as they are expected to be at much higher risk of relapse and development of metastatic disease,” Dr. Vinarsky said.
These ctDNA tests can stratify patients into groups – those needing aggressive treatment and those who may require only a shortened course of therapy or observation only.
This testing can also help identify patients who, despite being completely asymptomatic, may already be in the process of early relapse, allowing doctors to intervene before the disease becomes visible on imaging studies such as CT scans, PET scans or MRIs.
“Other implications include long-term monitoring,” Dr. Vinarsky continued. “If a high-risk patient finishes preventative treatment, the same technology can be used for follow-up. If a blood test that was previously negative suddenly turns positive, showing circulating cancer cells, we can begin treatment before any signs of active cancer appear on imaging studies.”
If monitoring shows a patient is not responding to treatment, doctors can make adjustments before visible tumor growth shows up on a scan.
“If there’s an increased amount of circulating DNA, we can alter the treatment program right away,” said Dr. Vinarsky. “It’s incredibly common for tumors to evolve and mutate. The cells don’t die – they keep growing and can develop resistance to a particular treatment. Circulating DNA testing helps us make decisions before there’s confirmation of relapse on imaging, which otherwise puts us behind and scrambling to get the patient back in remission. With this test, we can see when a treatment is no longer working and quickly devise another plan of attack.”
Circulating tumor DNA analysis represents a major step toward real-time, minimally invasive cancer management. From tailoring treatments to anticipating disease recurrence, its promise is vast – and its applications continue to grow.
Dr. Simon Vinarsky has practiced oncology for more than 20 years since completing his medical school training at Dnepropetrovsk State Medical Academy in Ukraine; his residency at New York Methodist Hospital, Brooklyn; and a fellowship at Long Island Jewish Medical Center, New Hyde Park, N.Y. He currently sees patients at the Scully-Welsh Cancer Center, 3555 10th Court, Vero Beach. Call 772-563-4673 for appointments.
