Liquid biopsies—blood tests that detect circulating tumor cells—may help healthcare providers predict which women with hormone receptor-positive (HR+) breast cancer are at higher risk of recurrence, according to the results of a study published in JAMA Oncology.

Blood tests measuring circulating tumor cells shed into nearby blood vessels by cancers that are growing and spreading aren’t new; they’re being studied in a number of ways to improve early detection, monitor disease progression, and help inform treatment decisions.

In the current study, researchers analyzed samples from 547 women with breast cancer with no signs of recurrence at least five years postdiagnosis. They found that 26 of the women had at least one detectable circulating tumor cell. A median of 2.6 years later, 24 of the 547 women experienced a recurrence: 7 of the 26 women with circulating tumor cells in the original liquid biopsy, and 17 who had no evidence of tumor cells earlier. This translated to a 13.1-fold higher risk of recurrence for patients with detectable circulating tumor cells.

When HR status was applied, women with recurrence of HR+ breast cancer had higher numbers detectable circulating tumor cells than those without recurrence. None of the women with HR- disease who had detectable circulating tumor cells developed recurrence. 

The researchers acknowledged that the study population was small and that longer-term studies are needed to validate the findings, but they hoped it may one day help practitioners predict which patients are candidates for long-term hormone therapy to prevent HR+ breast cancer recurrence and prevent use of unnecessary treatment in those who are not.