RELEVANCE

Most relevant for: People who have had or are considering liquid biopsy testing.
It may also be relevant for:

• people with metastatic or advanced cancer
• healthy people with average cancer risk
• people newly diagnosed with cancer

---

Liquid biopsies to guide treatment

Traditional biopsies, which remove pieces of a tumor so they can be studied for clues about a cancer, are very important for guiding treatment. However, liquid biopsies are becoming more common in situations where collecting samples of cancer cells is difficult or dangerous due to the size or location of the cancer. In these cases, the ability to find cancer cells or markers in the blood through liquid biopsies can spare patients the need for additional tissue biopsies. The most common uses for liquid biopsies after a diagnosis are:

• Identifying biomarkers that guide treatment selection
• Molecular residual disease (MRD) testing that detects tiny fragments of cancer after treatment

Treatment selection tests

Liquid biopsies are becoming more common to identify biomarkers for treatment selection. These tests are helpful when taking a tissue sample for traditional tumor biomarker testing is difficult or dangerous. Rather than looking directly at cancer cells in a tumor to find biomarkers for treatment, liquid biopsies search for evidence of cancer cell targets in the bloodstream. Examples include FoundationOne Liquid CDx and Guardant360 CDx test.

Minimal residual disease (MRD) tests

MRD (sometimes called molecular residual disease or measurable residual disease) tests look for evidence of cancer cells in the blood. It is difficult and risky to get a tumor sample of some cancers. Other cancers may be in hard-to-reach areas, such as the prostate. MRD tests may be used in the following ways:

• To identify people who would benefit from adjuvant treatment (after surgery).
• To identify people whose cancer is likely to recur (return).
• To help guide when and if tumor screening should be considered after treatment.
• To monitor a cancer to see if it is responding to therapy.
• To detect a cancer recurrence.

Signatera and Guardant Reveal are two examples of MRD tests.

What does this mean for me?

For people with cancer, liquid biopsies offer a non-invasive understanding of the cancer to help personalize treatment and monitor disease progression. Liquid biopsies for people with cancer are included in several cancer treatment guidelines, depending on cancer type and stage. For this reason, these tests are often covered by insurance plans, including Medicare.

If you have been diagnosed with cancer, depending on the type and stage, liquid biopsy testing may help guide or monitor your treatment. If you are newly diagnosed or if your cancer has stopped responding or recurred, liquid biopsy testing may also help identify the most effective treatment.

Questions for your doctor

• What is my risk for recurrence?
• How will you monitor my cancer when treatment ends?
• Is there a targeted therapy that might be more effective for my cancer? If so, will I need a tissue biopsy or is a liquid biopsy an option?

Reference

Agrawal, N. “Cancer-Detecting Blood Tests Are on the Rise. Do They Work?”, New York Times, December 2, 2025.

Disclosure: FORCE receives funding from industry sponsors, including companies that manufacture cancer drugs, tests and devices. All XRAYS articles are written independently of any sponsor and are reviewed by members of our Scientific Advisory Board prior to publication to assure scientific integrity.

Share your thoughts on this XRAY review by taking our brief survey.  

posted 2/6/26

Liquid biopsies and cancer screening

Liquid biopsies are blood tests that look for signs of cancer in the body, often by detecting small pieces of material released by cancer cells. Some liquid biopsies are being studied as a way to screen people who do not have symptoms of cancer, but most of these tests are still relatively new.

Single‑site liquid biopsy tests

Single-site liquid biopsy tests look for a specific type of cancer. Tests are being developed or studied for cancers such as colorectal, liver and pancreatic cancer. Many of these tests are still in the research phase.

One exception is Guardant Shield, a liquid biopsy test for colorectal cancer. This test is now included in national guidelines as an option for screening adults with average risk for colorectal cancer. However, colonoscopy remains the recommended screening method for people at high risk, because it allows doctors not only to find cancer early, but it also removes precancerous growths before they turn into cancer.

Multi-cancer detection (MCD) or Multicancer Early Detection (MCED) tests

These blood tests look for several types of cancer in a single test. Although doctors can now order these tests, as of this writing, none of the tests are FDA-approved to screen average or high-risk individuals, and none are included in national screening guidelines. For this reason, most insurance companies do not cover the cost of these tests. Research is ongoing to determine whether these tests can find cancer early enough to help people live longer after a cancer diagnosis.

Limitations of liquid biopsies for screening

The idea of using liquid biopsies for screening average-risk and high-risk people has generated a lot of interest. This is especially true for people with genetic mutations that are linked to more than one cancer, who often face a large screening burden. But these tests have costs and limitations, which vary by the specific test.

• Accuracy: None of these tests is perfect. It’s important to know how often false positives and false negatives occur with a given test.
• Identifying the source of the cancer: Some of the multi-cancer detection tests can only identify the presence of cancer, without pinpointing the type or source of the cancer. 
• Survival information is unknown. MCD tests are intended to detect cancers earlier. However, it is unknown if using these tests in the general public will improve survival and/or reduce deaths due to cancer.
• Not included in expert guidelines: Although MCD tests are available, there is not enough evidence to include them in expert guidelines.
• Out-of-pocket costs: The cost of MCD tests is hundreds of dollars, which is not currently covered by insurance.

Some clinical trials are studying liquid biopsies for cancer detection in average-risk and high-risk individuals. Participating in one of these studies is an opportunity to access these tests and contribute to progress in early detection research.

What does this mean for me?

Organizations such as the National Comprehensive Cancer Network (NCCN) publish expert guidelines for cancer screening, prevention and treatment. These guidelines are personalized by age, level of risk and cancer type. Separate guidelines are published for people with inherited mutations linked to cancer. Speak to your doctor about the current expert guidelines for cancer screening for someone of your age and situation. If you are interested in liquid biopsy to detect cancer early, consider participating in a clinical trial.

Questions for your doctor

• What is my risk for cancer?
• What are the current cancer screening recommendations for someone of my age and risk level?
• Am I eligible for any liquid biopsy screening clinical trials? 

Reference

Agrawal, N. “Cancer-Detecting Blood Tests Are on the Rise. Do They Work?”, New York Times, December 2, 2025.

Disclosure: FORCE receives funding from industry sponsors, including companies that manufacture cancer drugs, tests and devices. All XRAYS articles are written independently of any sponsor and are reviewed by members of our Scientific Advisory Board prior to publication to assure scientific integrity.

Share your thoughts on this XRAY review by taking our brief survey.  

posted 2/6/26