Common gut bacteria can fuel the growth of tumours in prostate cancer patients and allow them to evade the effects of treatment, scientists have found.
Prostate cancer is commonly treated with hormone therapy, which works by suppressing male hormones, called androgens.
But British scientists have found that having low androgen levels can drive the expansion of gut bacteria, which can then ‘take over’ hormone production.
The study, by the Institute of Cancer Research in London, identified ‘bacterial fingerprints’ which may help identify patients who’ll become resistant to treatment.
These men could benefit from strategies to manipulate their gut microbiome, the researchers suggest.
For example, men could undergo a faecal transplant or researchers hope to produce yoghurt drink enriched with favourable bacteria.
Prostate cancer kills 11,800 men a year in Britain, the equivalent of one every 45 minutes, and 26,000 men in the US each year.
Gut bacteria are normally beneficial to human health but a new study has found they can sometimes help feed the tumours in prostate cancer.
Study author and professor of experimental cancer medicine Johann de Bono said: ‘Our findings reveal that the initiation of hormone therapy for prostate cancer can trigger ‘gut bugs’ to start producing androgen hormones.
‘These androgens can then sustain prostate cancer’s growth and drive resistance to hormone therapy – worsening men’s survival outcomes.’
Professor de Bono added that while more research is needed, the discovery could lead to new treatments that manipulate gut bacteria to act in patients’ favour.
This could take the form of a yogurt drink with live bacteria that don’t produce the cancer fueling hormones, or a faecal transplant from another person with different gut bacteria.
A faecal transplant is the transfer of stool from a donor into the gastrointestinal tract of a patient.
It is most commonly used to treat recurring C. difficile infection – spread by bacterial spores found within faeces where it is 90 per cent effective.
Gut bacteria are part of our microbiome, a collection of microorganisms that normally live in the body, and are usually valuable to humans by aiding digestion.
However, cancer and other diseases can ruin this balance – for example, by promoting the expansion of gut bacteria and encouraging them to release toxins or other molecules that affect cancer cells.
The study found that getting rid of all gut bacteria in mice with prostate cancer slowed tumour growth and delayed the emergence of hormone resistance.
It further revealed that transplanting faeces from mice with hormone-resistant prostate cancer into mice with low androgen levels that had not yet developed resistance encouraged tumour growth.
Professor Kristian Helin, chief executive of the ICR, said the results of the study represented a new way of looking at cancer
‘The influence of the gut microbiome on cancer is a fascinating new area of science that we are just beginning to understand,’ he said
WHAT IS PROSTATE CANCER?
How many people does it kill?
More than 11,800 men a year – or one every 45 minutes – are killed by the disease in Britain, compared with about 11,400 women dying of breast cancer.
It means prostate cancer is behind only lung and bowel in terms of how many people it kills in Britain.
In the US, the disease kills 26,000 men each year.
Despite this, it receives less than half the research funding of breast cancer and treatments for the disease are trailing at least a decade behind.
How quickly does it develop?
Prostate cancer usually develops slowly, so there may be no signs someone has it for many years, according to the NHS.
If the cancer is at an early stage and not causing symptoms, a policy of ‘watchful waiting’ or ‘active surveillance’ may be adopted.
Some patients can be cured if the disease is treated in the early stages.
But if it diagnosed at a later stage, when it has spread, then it becomes terminal and treatment revolves around relieving symptoms.
Thousands of men are put off seeking a diagnosis because of the known side effects from treatment, including erectile dysfunction.
Tests and treatment
Tests for prostate cancer are haphazard, with accurate tools only just beginning to emerge.
There is no national prostate screening programme as for years the tests have been too inaccurate.
Doctors struggle to distinguish between aggressive and less serious tumours, making it hard to decide on treatment.
Men over 50 are eligible for a ‘PSA’ blood test which gives doctors a rough idea of whether a patient is at risk.
But it is unreliable. Patients who get a positive result are usually given a biopsy which is also not foolproof.
Scientists are unsure as to what causes prostate cancer, but age, obesity and a lack of exercise are known risks.
Anyone with any concerns can speak to Prostate Cancer UK’s specialist nurses on 0800 074 8383 or visit prostatecanceruk.org
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