Liquid Biopsy Assay Predicts Risk of Breast Cancer Relapse

A liquid biopsy method for tracking mutations in circulating breast cancer cells enables physicians to predict cancer recurrence as early as eight months before physical symptoms appear.

Predicting whether a cancer patient will relapse remains a formidable challenge in modern medicine. Fortunately, circulating tumor DNA (ctDNA) present in the blood may give clues on residual disease, cancer cells left behind that have the potential to seed new tumors even after treatment.

Investigators at the Institute of Cancer Research (London, United Kingdom) examined whether analysis of ctDNA in plasma could be used to monitor for minimal residual disease (MRD) in breast cancer. They used a "mutation tracking" digital polymerase chain reaction (PCR) technique to analyze samples from a prospective cohort of 55 early breast cancer patients receiving neoadjuvant chemotherapy.

They reported that detection of ctDNA in plasma after completion of apparently curative treatment—either at a single postsurgical time point or with serial follow-up plasma samples—predicted metastatic relapse with high accuracy. Mutation tracking in serial samples increased sensitivity for the prediction of relapse, with a median lead time of 7.9 months over clinical relapse.

The investigators further demonstrated that targeted capture sequencing analysis of ctDNA could define the genetic events of MRD, and that MRD sequencing predicted the genetic events of the subsequent metastatic relapse more accurately than sequencing of the primary cancer. Thus, mutation tracking could identify early breast cancer patients at high risk of relapse.

Senior author Dr. Nicholas Turner, team leader in molecular oncology at The Institute of Cancer Research, said, "We have shown how a simple blood test has the potential to accurately predict which patients will relapse from breast cancer, much earlier than we can currently. We also used blood tests to build a picture of how the cancer was evolving over time, and this information could be invaluable to help doctors select the correct drugs to treat the cancer. Ours in the first study to show that these blood tests could be used to predict relapse. It will be some years before the test could potentially be available in hospitals, but we hope to bring this date closer by conducting much larger clinical trials starting next year. There are still challenges in implementing this technology, but digital PCR is relatively cost-effective and the information that it provides could make a real difference to breast cancer patients."

The study was published in the August 26, 2015, online edition of the journal Science Translational Medicine.

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