October 6, 2023
October 6, 2023

Liquid Biopsy: The Promises and Limitations for Early Cancer Detection

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Liquid Biopsy: The Promises and Limitations for Early Cancer Detection

Over 50 years of research confirms that 90% of cancer deaths are caused by secondary tumors that have spread from the original location. 

Let that sink in. Suddenly, the idea of early detection feels a lot more important.

Early detection refers to the identification of a disease before symptoms start. It involves tests, examinations, imaging, and other procedures that can be done quickly and easily.

Because early detection and targeted cancer therapy can lead to better survival rates, cancer researchers are always looking for new ways to find cancer sooner and prevent disease progression. 

Here, we’re breaking down the ins and outs of liquid biopsy cancer screening. We’ll share easy-to-understand descriptions and explanations and how liquid biopsies compare to traditional biopsies. We’ll also reveal what to expect during a liquid biopsy and other methods of non-invasive testing.

How Is a Liquid Biopsy Different from a Traditional Biopsy?

Liquid biopsy cancer screening is a fairly new and minimally invasive method for detecting and monitoring cancer in patients. Instead of removing flesh like a traditional tissue biopsy, a sample of your blood or other body fluids (urine, saliva, stool) might help healthcare providers find out if you have cancer.

Thanks to the breakthrough of genomic sequencing (how scientists decode our genetic material), we can now use liquid biopsy technology to look for important clues that guide cancer treatment. Specifically, the tests look for something called “tumor-derived genetic material.” This is basically “tumor DNA.” It’s also called cell-free DNA (cfDNA), exosomes, and extracellular vesicles (membrane structures existing outside our cells).

In summary, during a biopsy, the healthcare provider takes a sample of the tumor and tests the cells to see if they are cancerous. In contrast, a liquid biopsy detects signs of a tumor, tumor cells, and tumor DNA that may be present in your blood.

Are Liquid Biopsies Better Than Tumor Biopsies?

One advantage of liquid biopsies is their speed. Traditional tumor tissue biopsies can take days or even weeks to obtain results because the process involves sample collection, processing, and histological analysis (looking at it under the microscope). However, with only a blood sample needed, liquid biopsies may lead to early cancer detection quicker than tissue biopsies.

For example, as reported in the journal Clinical Lung Cancer, liquid biopsies had faster results than tissue biopsies in non-small cell lung cancer. A liquid biopsy can provide results within a matter of days or even hours, as the genetic material can be rapidly isolated, analyzed, and reported – sometimes in real time.

Additionally, liquid biopsies may offer more cancer information compared to traditional screening tools, including tissue biopsies. For example, tissue samples can only provide information about the specific area sampled, which may not fully represent heterogeneity (characterization of a tumor’s composition). 

Liquid biopsies might be able to detect different changes in genes, whether they are genetic (inherited) or genomic (caused by the environment). This means they can provide a detailed look at the specific characteristics of a cancer from various parts of the body. Since the tests can be easily repeated to track changes, they improve active monitoring and more personalized treatment decisions.

How Does a Liquid Biopsy Compare to Tumor Markers?

When we talk about a liquid biopsy cancer screening, the topic of other biomarkers like tumor markers often comes up. Per the National Cancer Institute, tumor markers are substances (usually proteins)made at higher amounts by cancer cells than normal cells.

Tumor marker tests are for patients at high risk for getting certain cancers. For example, PSA is a biomarker for prostate cancer, and CA-125 can help detect early signs of ovarian cancer in women at high risk. There are several pros and cons to using tumor markers for early cancer detection and cancer screening.


  • Simple blood tests requiring only a peripheral blood draw from your arm or other specimen
  • Inexpensive
  • May be used for cancer screening
  • Helps to diagnose cancer early 
  • May be used to monitor cancer patients


  • Not all cancers produce tumor markers
  • Tumor markers can be affected by other factors
  • Higher number of false positives and false negatives
  • Tumor markers may not be accurate enough to detect cancer early
  • Tumor markers cannot be used to determine the stage or type of cancer

What Types of Cancer Can a Liquid Biopsy Detect?

There are two sides to the liquid biopsy coin. One side is “cancer detection” and the other is “cancer monitoring.” 

The success rate for detecting cancer cells in blood or body fluids depends on the sensitivity of the test and the number of abnormal cells in the sample. Because certain types of cancers and cancers that are actively growing shed more abnormal cells, they are easiest to detect. 

Currently, liquid biopsies are excellent at detecting and monitoring non-small cell lung cancer (NSCLC). Other liquid biopsy tests are successful for monitoring cancer changes in patients with cancer or pre-cancer.

What Are the FDA-Approved Liquid Biopsy Tests?

With ongoing research and many new developments on the horizon, it’s an exciting time for oncology researchers and clinicians. When it comes to liquid biopsies, you might wonder where the technology stands in terms of discovery, FDA approval, and availability. 

To make things easier to understand, here’s a brief timeline: 

1869: Thomas Ashworth observes circulating tumor cells (CTC) in a patient with advanced cancer.

1948: Researchers detect and measure the amounts of cell-free DNA (cfDNA) in both healthy and diseased patients. 

1966: Researchers discover high levels of cfDNA in patients with lupus. 

1980s: Scientists find cfDNA in cancer patients.

1994: Scientists detect mutations in cfDNA. A “mutation” is cell damage caused by cancer or other disease processes.

2004: The Food and Drug Administration (FDA) approves the use of CellSearch Circulating Tumor Cell to monitor cancer in people with advanced breast cancer, colorectal cancer, and prostate cancer. This liquid biopsy analyzes a blood sample for the presence of circulating tumor cells (CTCs), which are tumor cells that have broken away from the primary tumor and entered the bloodstream.

2014: FDA approves the CancerSEEK test, which is a multi-cancer early detection test that looks for eight different cancer-related biomarkers in blood. The CancerSEEK test is not approved for monitoring cancer.

2021: The FDA approves Guardant360 CDx, a liquid biopsy that detects mutations in the DNA of tumor cells in the blood. The Guardant360 CDx test is approved for use in people with non-small cell lung cancer (NSCLC) to help guide treatment decisions.

2021: FDA approves the FoundationOne Liquid CDx test, which is a liquid biopsy that detects mutations in the DNA of tumor cells in the blood. The FoundationOne Liquid CDx test is approved for use in people with NSCLC, prostate cancer, ovarian cancer, and breast cancer to help guide treatment decisions.

Note that not all liquid biopsy tests are FDA-approved and may be available for use through other means.

The Future of Liquid Biopsy

Liquid biopsies are still a developing technology, but they have the potential to make a significant impact on the fight against cancer. They could be used to:

  • Detect cancer at earlier stages
  • Monitor cancer treatment and predict recurrence
  • Select patients for targeted therapies

What Can I Expect During a Liquid Biopsy?

Liquid biopsy: doctor inserting a needle into his patient's arm

Before the test, your doctor will write a prescription and you'll want to verify if the test is covered by your insurance. This can be done by contacting your insurance company or speaking to your doctor.

During the test, a trained phlebotomist will draw a small sample of blood from your arm. These medical professionals are skilled in performing this procedure to minimize discomfort and ensure proper collection of the sample.

After the test, it typically takes around a week to receive the test results. Your doctor will inform you about the results and discuss any necessary follow-up actions or treatment plans based on the findings. Be sure to follow up with your doctor regarding the test results.

What Are Some Drawbacks of Liquid Biopsy Cancer Screenings?

While liquid biopsies have shown promise as a non-invasive alternative to traditional biopsies, their accuracy can vary based on several factors. These factors include the type and stage of the cancer being tested and the amount of circulating CTCs and ctDNA present in the sample. This means it may not be sensitive enough to detect all cases and types of cancer, especially at an early stage. 

Liquid biopsies are expected to become more accurate and inclusive as cancer research progresses. More clinical trials and research are needed to optimize liquid biopsies. Until then, according to the College of American Pathologists, a liquid biopsy does not replace a tissue-based biopsy.

Is There Another Early Screening Option to Liquid Biopsies?

An Ezra Full Body Scan is another approach to screening. It includes an MRI of 13 organs with the possibility of including a low-dose chest CT scan if necessary.

An annual screening MRI helps monitor your body over time and may help radiologists notice abnormalities sooner. The Ezra Full Body Scan covers various vital organs, including the brain, neck, spine, abdomen, and pelvis. This scan can help detect potential abnormalities such as tumors, cysts, or other structural irregularities.

Choose Early Detection of Cancer to Improve Health Outcomes

Although they’re still being developed and validated for widespread use, liquid biopsies hold promise as valuable tools in cancer diagnosis, monitoring, and precision medicine (personalized treatment).

Early detection can help improve cancer outcomes by providing care and management at the earliest possible stage. If cancer is caught before it metastasizes or spreads too far, it’s more likely to be treated successfully. For this reason, it’s vital to get proactive screening tests like the Ezra Scan.

An Ezra Full Body MRI Scan can aid in detecting potential cancer. This type of proactive screening test is designed to empower you with an advanced imaging modality that is accurate, fast, non-invasive, and cost-effective. 

The entire sign-up process is done online and takes less than 10 minutes. You can avoid fees by using your health savings account (HSA) or flexible spending account (FSA). Book your appointment today.