The ECOG-ACRIN Cancer Research Group in the US has demonstrated a new method of measuring circulating tumour cells (CTCs) in the blood for predicting high or low risk of a breast cancer relapse.
In a proof-of-concept study, the researchers analysed CTCs from samples of 547 patients who were cancer-free five years after diagnosis, followed by related CTC with a later recurrence.
ECOG-ACRIN Cancer Research Group vice-chair Joseph Sparano said: “Late recurrence five or more years after surgery accounts for at least one-half of recurrences of breast cancer, and there are no tests that identify who is at highest risk.
“We found that, in women who were cancer-free five years after diagnosis, about 5% had a positive CTC test.”
Results further indicated that a positive test was associated with 35% relapse risk after two years, compared to 2% for patients who tested negative for CTC.
Existing CTC blood test has been approved by the US Food and Drug Administration (FDA) for monitoring response to treatment in patients with advanced stage breast, colon or prostate cancer.
The purpose of the latest study was to show the use of a blood test to customise treatment for decreasing the risk of relapse in high-risk patients as well as to provide spare therapy for people at low risk.
Sparano added: “The findings of this analysis provide strong evidence to further evaluate this new risk assessment approach using CTC and other blood-based tests in this setting.”