A new sensitized blood test can help clinicians discover when breast cancers become resistant to standard hormone therapy.1

Results from one study showed that blood sample analyses that tested the circulating tumor DNA (ctDNA) could provide early warning for mutations to the estrogen receptor gene ESR1, which serves as an indicator that resistance to aromatase inhibitors is occurring. Aromatase inhibitors block or suppress estrogen, however mutations in the ESR1 gene can help tumors evade and resist these hormone therapies.

Dr. Lajos Pusztai, MD, DPhil, of Yale Cancer Center in New Haven, CT, who was not affiliated with the study, told Cancer Therapy Advisor  that the novelty of the study’s findings is that the use of a blood assay helps clinicians use a less invasive method than tissue analysis to identify patients with mutations.

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Dr. Nicholas Turner, MD, team leader in molecular oncology at The Institute of Cancer Research in London, United Kingdom, said in a statement sent by the institute “The test could give doctors an early warning of treatment failure and, as clinical trials of drugs that target ESR1 mutations are developed, help select the most appropriate treatment for women with advanced cancer.”

Ultra-sensitive Blood Test

In the study, Gaia Schiavon and researchers from The Institute of Cancer Research and The Royal Marsden Hospital, both in London, United Kingdom, took blood samples from 171 women with advanced estrogen receptor (ER)-positive breast cancer to find ESR1 mutations. Of those who were given aromatase therapy, none had an ESR1 mutation prior to starting treatment.

They then validated the results in 3 independent groups of patients.