Blood tests for cancer are no longer a side option to a tissue biopsy. A liquid biopsy looks in a blood sample for circulating tumor DNA (ctDNA), circulating tumor cells, RNA and other molecular signals, and in many cases it can do what once required tissue: profile a tumor, help choose a therapy, track how treatment is working, and flag disease that remains or returns.
A market growing fast
Towards Healthcare projects the global liquid biopsy market will climb from USD 7.08 billion in 2025 to USD 27.42 billion by 2035, a compound annual growth rate of 14.5%. The U.S. share alone is forecast to rise from USD 2.78 billion in 2026 to USD 8.90 billion by 2035. North America leads today, and Asia Pacific is expected to grow fastest.
That growth rests on different uses with different standards of proof: precision oncology, targeted therapy, monitoring, and screening of healthy people. A test that guides treatment in someone who already has cancer is a different product from one that screens people with no symptoms, and approval, insurance coverage and proof of benefit apply to each separately.
What is happening in the clinic
Some of the news is concrete. On October 8, Guardant Health announced European approval of Guardant360 CDx as a companion diagnostic for AstraZeneca’s camizestrant in advanced estrogen receptor-positive breast cancer. In September, an FDA advisory panel voted 7 to 2 that the benefits of Grail’s Galleri test, built to pick up signals from more than 50 cancer types, outweighed its risks. An advisory vote is not an approval, and questions remain about sensitivity, false positives and whether screening actually improves outcomes.
After surgery, ctDNA testing can show whether molecular traces of cancer are still present and may help predict recurrence. Quest Diagnostics said its Haystack MRD test is now authorized in all 50 states, and Natera’s Signatera won Japanese approval for adjuvant colorectal cancer use.
Doctors still argue about what to do with the result. At the Northeast GI Oncology Congress, set for November 19 to 21 in Boston, one debate will ask whether ctDNA should guide adjuvant treatment in colorectal, gastroesophageal and pancreatic cancers. If a result is positive, which step follows? If negative, how much evidence is needed before treatment is scaled back? Early findings suggest the signal is useful, but acting on it has to be shown to help patients.
Looking for breast cancer earlier
Researchers at USC Norris Comprehensive Cancer Center have started a trial of a blood test aimed at breast cancer as early as Stage I. Most current liquid biopsies hunt for small pieces of DNA, which are hard to find in a small tumor. This test looks for rare cancer-associated cells and for large extracellular vesicles, or L-EVs, tiny particles that cancer cells release and that appear to be detectable at the earliest stages.
“Our hope is to determine whether this test can provide more information about breast cancer screening and detection, particularly during the stages of the disease when it may be easier to treat,” said Dr. Anastasia Martynova, the principal investigator. Dr. Amanda M. Woodworth, director of breast health at Keck Medicine, pointed to women who live far from screening services or who have had a mastectomy and can no longer have mammograms. The encouraging part is that the test could one day reach them.
It is still an experiment, and it does not replace mammograms or breast biopsies. Patients who are curious about liquid biopsy, or who face barriers to screening, should talk to their doctor about what is available now. Each participant gives two blood samples a year apart, and the results are compared with their diagnoses. If this phase 1 trial goes well, the team plans a larger phase 2 study.
Sources
- Liquid Biopsy Market Research to Reach USD 27.42 Billion by 2035 as Cancer Blood Tests, AI Diagnostics and Precision Oncology Advance
- From Liquid Biopsy to New Treatment Modalities: What to Expect at Northeast GI Oncology Congress 2026 – OncoDaily
- Clinical trial to evaluate blood test for early detection of breast cancer
Photo: Welsh Government (OGL 3)
