A simple blood test could catch breast cancer earlier than mammograms alone

Researchers at USC Norris Comprehensive Cancer Center have kicked off a clinical trial to find out whether a blood test can catch breast cancer earlier — and more reliably — than mammograms alone. The liquid biopsy, developed at USC's Michelson Center, looks for two things: rare cancer-associated cells and tumor-associated large extracellular vesicles (L-EVs), tiny particles that cancer cells release into the bloodstream early in disease development. Unlike most existing liquid biopsy tests that hunt for cancer DNA fragments (which can be hard to spot when tumors are small), this approach may offer a clearer signal at the earliest stages.

The trial will collect two blood samples from participants one year apart, comparing results against actual diagnoses to gauge accuracy. Researchers are also exploring whether the test could broaden access to screening — particularly for women in remote areas or those who've had mastectomies and can no longer use mammograms.

Key Takeaways:

• The test does not replace mammograms or biopsies — it's designed to complement existing screening
• Positive Phase 1 results would trigger a larger Phase 2 trial
• The underlying technology could eventually be adapted to screen for lung, colon, and other solid tumor cancers

Why it matters: Over 300,000 U.S. women are diagnosed with breast cancer annually. Earlier detection means easier treatment — and this blood test could reduce the anxiety-filled waiting periods that often follow ambiguous mammogram results.