USC Norris Comprehensive Cancer Center, part of Keck Medicine of USC, has initiated a Phase I clinical trial to determine whether a blood test can detect breast cancer earlier than standard mammograms.

The liquid biopsy is intended for use alongside regular screening to detect cellular and molecular markers of early-stage disease.

Specifically, it detects rare cancer-associated cells and tumour-associated large extracellular vesicles that enter the bloodstream during early disease development.

According to USC, over 300,000 women receive a breast cancer diagnosis in the US each year.

While mammography remains the standard screening method, abnormal results frequently require supplementary imaging, tissue biopsies, or follow-up examinations after six months.

These intervals can heighten patient anxiety and delay necessary care if malignancy is present.

USC Norris breast cancer specialist and medical oncologist and trial principal investigator Anastasia Martynova said: “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.”

Conventional liquid biopsies are predominantly deployed after diagnosis to track therapeutic response or cancer recurrence, typically by identifying fragmented tumour deoxyribonucleic acid (DNA).

Because such genetic markers are difficult to identify in small, early-stage tumours, the experimental assay instead isolates rare cells alongside extracellular vesicles to reflect early cellular activity.

Study participants will provide two blood samples across a 12-month interval to compare against diagnostic findings. The diagnostic tool remains investigational and does not replace mammography or biopsies.

The assay was created at the USC Michelson Center Convergent Science Institute in Cancer by the USC Dornsife College of Letters, Arts and Sciences University professor and biological sciences dean professor Peter Kuhn.

Should Phase I yield positive results, investigators plan to proceed with a larger Phase II trial. The underlying technique may also eventually be applied to screen for other solid tumours, including colon and lung cancers.