A new 3-in-1 blood test could revolutionise the treatment of prostate cancer, say scientists, and help pave the way for personalised patient treatment.
The key to the new treatment is the ability to test for cancer DNA in a person's bloodstream. This so-called 'liquid biopsy' has the advantage of being cheaper and less invasive than traditional biopsies.
The blood test is still in early clinical trials involving only a few patients but scientists say it could be used in 3 ways:
- Men with advanced prostate cancer could be checked to see if they would benefit from treatment with new drugs called PARP inhibitors – which can help stop cancer cells from repairing themselves, causing the tumour cells to die
- An analysis of DNA in people's blood after they had started a specific course of treatment can check whether it is working and if not, switch them to an alternative treatment
- Monitor a patient's blood throughout treatment to check whether the cancer is evolving to become resistant to the drugs being used
The team from The Institute of Cancer Research (ICR) in London and The Royal Marsden NHS Foundation Trust say it is the first time a test has been developed to aid targeted cancer therapy for specific genetic faults within cancer tumours.
They say it could one day lead to a PARP inhibitor called olaparib becoming standard treatment for advanced prostate cancer.
Some patients respond to treatment with olaparib for years but in other patients, the treatment either fails early, or the cancer evolves resistance. This means that cancer cells regain the ability to repair themselves, causing tumours to grow.
Reducing Cancer DNA in the Blood
Using the new blood test, the researchers report that patients who responded to olaparib saw an average fall in the levels of circulating cancer DNA of 49.6% after just 8 weeks of treatment. This compared to an average rise of 2.1% in patients who did not respond to the drug.
Men whose blood levels of DNA had decreased at 8 weeks after treatment survived an average of 17 months, compared with only 10.1 months for those whose cancer DNA levels remained high.
The study, in the journal Cancer Discovery, involved samples taken from 49 men at The Royal Marsden with advanced prostate cancer enrolled in a phase II clinical trial of olaparib.
The results have drawn comments from several experts in the field. Professor Paul Workman, chief executive of the ICR, says "Blood tests for cancer promise to be truly revolutionary. They are cheap and simple to use, but most importantly, because they aren’t invasive, they can be employed or applied to routinely monitor patients to spot early if treatment is failing – offering patients the best chance of surviving their disease."
Professor David Cunningham, director of clinical research at The Royal Marsden NHS Foundation Trust, comments: "This is another important example where liquid biopsies – a simple blood test as opposed to an invasive tissue biopsy – can be used to direct and improve the treatment of patients with cancer."
Dr Matthew Hobbs, deputy director of research at Prostate Cancer UK says: "To greatly improve the survival chances of the 47,000 men diagnosed with prostate cancer each year, it’s clear that we need to move away from the current one-size-fits-all approach to much more targeted treatment methods.
"The results from this study and others like it are crucial as they give an important understanding of the factors that drive certain prostate cancers, or make them vulnerable to specific treatments.
"However, there is still much more to understand before the potentially huge benefits of widespread precision treatment for prostate cancer will reach men in clinics across the UK."