Could liquid biopsy replace PSA for prostate cancer?

2019 06 19 21 28 0345 Prostate 3 D 400

A liquid biopsy blood test that identifies the earliest genetic changes of prostate cancer has been developed by researchers from the U.K., who believe it could potentially replace prostate-specific antigen (PSA) testing, according to a study published online March 9 in the Journal of Clinical Investigation.

The test detects a prostate cancer biomarker that signals the disease is active and could help clinicians better monitor prostate cancer response to treatment, wrote a team led by doctoral candidate Anjui Wu of University College London (UCL) Cancer Institute.

"Metastatic prostate cancer -- the most dangerous late stage of the disease -- can vary substantially in its treatment response and clinical progression," Wu said in a statement released by UCL. "We urgently need biomarkers that will help us determine how far along each patient's cancer is, to determine the best course of treatment. With [tumor] biopsies difficult to obtain, being able to identify prostate cancer DNA signatures at the earliest opportunity in blood will help monitor patients better and assist more effective treatment selection and combination."

The analysis of plasma DNA mutations via blood tests shows promise for informing treatment decisions in cancer patients, the group wrote. Not only does plasma DNA contain genomic information, it also contains information about DNA methylation, a chemical change in DNA molecules that can affect gene function, which can be used to assess tumor composition.

Although researchers previously have used methylation information from plasma DNA to identify a cancer's tissue of origin, it hasn't been investigated as much in patients with metastasized cancer. To address this knowledge gap, Wu et al sought to investigate the tracking of DNA methylation in metastatic, castration-resistant prostate cancer.

Wu and colleagues used next-generation sequencing to analyze the methylation and genomic profiles of circulating cell-free DNA from 25 patients and included an analysis of four healthy blood plasma samples for a control cohort.

They discovered 1,000 methylation alterations particular to the prostate gland in the blood samples from the study participants.

"Our study identified methylation changes in 1,000 genomic segments that can be used to track circulating tumor DNA," the group wrote. "This could address some of the challenges inherent in plasma genomic studies."

It's possible that liquid biopsy could complement or even substitute for the traditional serum PSA test used for diagnosis, risk assessment, and treatment monitoring, said corresponding author Dr. Gerhardt Attard, PhD.

"We believe the increased sensitivity and additional information we derive will significantly improve the outcomes of men with advanced prostate cancer," he said in the UCL statement.

The study results further demonstrate that the liquid biopsy field shows great potential to improve the diagnosis and management of cancer patients, according to Dr. Mark Emberton, dean of the faculty of medical sciences at UCL.

"This test could be the first to tell us cancer has got into blood before the spread is large enough to see on imaging," he said.

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