June 21, 2018

Soon a diagnosis by simple blood test?

Diagnosing (not screening) prostate cancer by a simple blood test: this is the project on which works Dr. Catherine Alix-Panabières and a team of European researchers at CHU Montpellier. A method that would be more reliable and less invasive than a standard prostate tissue biopsy.

With 12 men diagnosed daily in Quebec and almost 900 deaths estimated in 2017, prostate cancer is the most common among men over 50 years of age.

Today, this male cancer is still diagnosed mainly by a biopsy performed transrectally. An invasive and uncomfortable method for the patient that is far from being perfectly effective: besides the risks of infections associated with this procedure, the biopsy occasionally passes by aggressive (cancerous) tumor cells.

A team of European researchers led by Catherine Alix-Panabières plans to end this invasive method of diagnosing prostate cancer. At Montpellier University Hospital, she is working on a diagnosis that can be made by simply taking blood, known as liquid biopsy.

What is a liquid biopsy?

A liquid biopsy looks for signs of cancer in a person’s bodily fluid – most often blood, but also urine, saliva, semen or other fluids.

In recent years, research into liquid biopsy has flourished. While it isn’t routinely used for cancer diagnosis yet, it is starting to be used in people who have already been diagnosed with cancer for a couple of purposes: for monitoring whether the tumour is growing and for identifying and analysing the genetic material of the tumour.

More reliable and less invasive screening than transrectal biopsy

According to Dr. Catherine Alix-Panabières, this liquid biopsy performed via a blood sample, has many advantages. Less invasive than a tissue biopsy, it would combine several prostate cancer biomarkers: circulating cancer cells (CTC), circulating tumor DNA and exosomes.

Circulating tumour cells (CTCs): As a tumour grows, it releases whole cells that enter the bloodstream and travel around the body. These cells, called circulating tumour cells (CTCs) can be detected in a blood sample and indicate that cancer is present.

Circulating tumour DNA (ctDNA): As cancer cells die, they release fragments of their genetic material into the blood, which is known as circulating tumour DNA (ctDNA). These bits of cancer DNA can be detected by specialized equipment and alert researchers to cancer’s presence.

Exosomes: These are microscopic vesicles (portion of cancer cells) that escape and circulate in the blood. Prostate cancer exosomes play an important role in the growth of cancer cells and the progression of the disease.

For doctors and researchers, circulating biomarkers also offer the possibility of specifying the prognosis of a cancer or of quickly detecting a resistance to a treatment, or even a relapse before it is clinically visible.

For Dr. Catherine Alix-Panabières, this method will provide a diagnosis as reliable or even more reliable than that achieved through the standard biopsy.

"The goal is also to personalize the treatment, to give the right treatment to the right person at the right time. It is a precision medicine,"says the teacher-researcher, who has seen her work be subsidized to conduct a clinical study of 1,000 patients.

References

Cancer de la prostate : bientôt un dépistage par simple prise de sang

Société canadienne du cancer

Prostate cancer exosomes as modulators of the tumor microenvironment 

Alex P. Shephard*, Vincent Yeung*, Aled Clayton, Jason P. Webber

J Cancer Metastasis Treat 2017;3:288-301.  | https://doi.org/10.20517/2394-4722.2017.32 | © The Author(s) 2017

Written by PROCURE. © All rights reserved - 2018

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