March 20, 2023
March 20, 2023

Liquid Biopsy for Cancer: A Patient’s Guide

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Liquid Biopsy for Cancer: A Patient’s Guide

Editor’s note: This blog post was medically reviewed by Carol DerSarkissian, MD

In recent years, a cancer screening tool called liquid biopsy is becoming a simple and less invasive option to traditional tissue biopsies.

This guide will focus on the ins and outs of liquid biopsies, including what they are, how they compare to traditional biopsies, and what to expect during a liquid biopsy.

Table of contents

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What is a Liquid Biopsy and Why You Might Need One?

Liquid biopsy is a new, promising, real-time cancer detection and monitoring approach. It involves testing a patient’s blood for signs of cancer. It’s also possible to use other bodily fluids like urine and saliva.

The technique relies on the fact that cancer cells shed small amounts of DNA, RNA, and proteins into the bloodstream.

During a liquid biopsy, doctors collect a sample of bodily fluids and process it in a laboratory to isolate the circulating tumor cells (CTCs) or circulating tumor DNA (ctDNA) associated with cancer.

CTCs and ctDNA can also supply genetic information about cancer, aiding your healthcare provider in deciding what cancer treatments may work best.

A healthcare provider may recommend a liquid biopsy to:

  • Establish your prognosis. Your healthcare provider can perform periodic liquid biopsies to monitor your condition and adjust your treatment for some specific cancers.
  • Decide on treatment. Liquid biopsies can show if certain types of targeted therapy treatments may be right for you in your cancer care of some specific cancers.

Your healthcare provider may recommend a liquid biopsy if you have metastatic or advanced cancer and aren’t responding to treatment. They may also recommend a liquid biopsy if a traditional biopsy is not possible or results are needed more quickly.

How Does a Liquid Biopsy Compare to a Traditional Biopsy?

A tissue biopsy is the most common approach to cancer screening, diagnosis, and monitoring. It involves taking a tumor tissue sample from the affected area and examining it under a microscope.

This approach, however, can be invasive, costly, and time-consuming and may not always be possible to provide enough information to guide treatment decisions.

On the other hand, liquid biopsies are less invasive and faster. They are similar to the routine blood test you may opt for to check your levels and monitor your health.

Less Invasive and Painful

One of the main advantages of a liquid biopsy is that it is less invasive and painful than a tissue biopsy. This makes it a more attractive option for patients who cannot undergo traditional biopsy due to their age, health status, or other factors.

Faster Turnaround Times

With only 5 milliliters of blood required, liquid biopsies may produce results quicker than tissue biopsies.

For example, liquid biopsies had faster results than tissue biopsies in non-small cell lung cancer. Survival outcomes were also similar regardless of whether liquid or tissue biopsies were used to guide cancer treatment decisions.

Potentially More Comprehensive

Liquid biopsy may also provide more comprehensive information about a patient’s cancer than a tissue biopsy. It can also help identify multiple tumor genes in the bloodstream at multiple time points.


While a liquid biopsy is a promising new approach to cancer diagnosis and monitoring, some challenges still need to be overcome.

For example, one of the main limitations of the technique is that it may not be sensitive enough to detect all cases and types of cancer, especially at an early stage. More clinical trials and research are needed to optimize liquid biopsies.

According to the College of American Pathologists, a “liquid biopsy” does not replace a tissue-based biopsy. For now, liquid biopsies can help confirm if a lump or lesion is indeed cancerous.

Are Liquid Biopsies Accurate?

While liquid biopsies have shown promise as a noninvasive 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.

Liquid biopsies are expected to become more accurate and inclusive as cancer research progresses.

For now, a standard biopsy is still needed to confirm a cancer diagnosis.

What are the Types of FDA-Approved Liquid Biopsies?

laboratory staff getting a blood sample

A few types of liquid biopsies are approved by the Food and Drug Administration (FDA).

These include the Cell Search® Circulating Tumor Cell (CTC) Test, cobas® EGFR Mutation Test v2, Guardant360® CDx, and FoundationOne® Liquid CDx.

CellSearch Circulating Tumor Cell (CTC) Test

Approved by the FDA in the early 2000s, the CellSearch CTC Test is the first liquid biopsy test to monitor cancer in people with metastatic breast cancer, colorectal cancer, and prostate cancer by detecting the amount of CTCs in their blood. It can help your healthcare provider monitor your condition.

Cobas EGFR Mutation Test v2 Test

Approved by the FDA in 2016, the Cobas EGFR Mutation Test v2 Test detects changes in the DNA from cancer cells in the blood of individuals with non-small cell lung cancer (NSCLC). The test helps your healthcare provider determine the best treatment for you.

Guardant 360 CDx Test

Approved by the FDA in 2021, the Guardant 360 CDx Test also detects ctDNA and is approved for use with cancer patients with NSCLC.

FoundationOne Liquid CDx Test

Approved by the FDA in 2021, the FoundationOne Liquid CDx Test also detects ctDNA and is approved for use in people with NSCLC, prostate, ovarian, and breast cancer.

What Can I Expect During a Liquid Biopsy?

blood extraction

A liquid biopsy is simple, fast, and straightforward compared to a standard biopsy.

Before the Procedure

One advantage of a liquid biopsy is that you do not need to take special precautions before the blood draw. Additionally, your doctor will tell you if you need to stop taking any medications before the procedure.

While it is becoming more common for public and private health insurance providers to cover liquid biopsies, you should contact your provider before getting a liquid biopsy to ensure your test will be covered under your plan.

During the Procedure

Your healthcare provider will take a blood sample and send it to a lab where a machine will separate your blood cells from your plasma. A specialist called a pathologist will then check for CTCs or ctDNA in the plasma.

After the Procedure

It typically takes about seven to ten days to get the results of a liquid biopsy back.

Rest assured that your doctor will explain the results of the test, answer any questions, and recommend next steps. For example, you might need further tests, such as an MRI or a CT scan, to find out if cancer cells has grown or spread.

The Importance of Early Detection in Cancer Outcomes

Early detection can help improve cancer outcomes by providing care and management at the earliest possible stage

If cancer is caught before it has a chance to spread too far, the treatment is more likely to work. For this reason, it’s important to pay attention to your body and speak up if something feels off.

Ezra offers a full-body MRI scan to aid in screening potential cancer. This type of proactive screening test is designed to empower individuals with an advanced imaging modality that is accurate, fast, noninvasive, and cost-effective.

It can scan 13 organs in approximately an hour and may detect early signs of certain cancers, including prostate, brain, pancreas, and ovarian cancers.

Book an Ezra full-body MRI scan today.

Not yet ready for a scan? Calculate your cancer risk in 5 minutes or less.

You can also schedule a call with our team to learn more. Contact us at (888) 402-3972 or