The researchers said their findings should lead to routine blood tests for prostate cancer patients / Getty Images


Some common treatments for prostate cancer may actually encourage tumour growth and make the disease worse, a major new study has found.

Findings published by the UK’s leading cancer research organisations found that a group of steroid drugs called glucocorticoids, while initially controlling the disease, were linked to mutations in cells that drive tumour growth.

Although only conducted in a small group of men, the researchers said their findings should lead to routine blood tests for prostate cancer patients, which could determine the point at which the steroids cease to be effective and become harmful.

The leading charity Prostate Cancer UK said that the study should be followed up in a bigger trial group, but urged men already using the steroids not to stop, and to consult their specialist if they had concerns.

Experts said that the study highlighted the major problem of cancer drug resistance – the process by which cancer cells in an individual evolve immunity to the drugs used to combat them. Professor Paul Workman, chief executive of the Institute of Cancer Research, which conducted the study along with the Royal Marsden Hospital and the University of Trento in Italy, said that drug resistance was “the single biggest challenge we face in cancer research and treatment”.

“We are just beginning to understand how its development is driven by evolutionary pressure on tumours,” he said. “This important discovery reveals how some cancer treatments can actually favour the survival of the nastiest cancer cells, and sets out the rationale for repeated monitoring of patients using blood tests, in order to track and intervene in the evolution of their cancers.”

Researchers used genetic analysis of tumour and blood samples to search for clues that use of glucocorticoids was helping cells with a particular mutation to survive.

In several of the patients, use of the steroids coincided with the emergence of such mutations, and also the progression of the cancer into more advanced forms.

Dr Matthew Hobbs, deputy director of research at Prostate Cancer UK, said a blood test could “arm doctors with the knowledge they need to ensure that no time is wasted between a drug that stops working for a man and him moving to another effective treatment”.

However, he said the blood test should be trialled in a larger group than the cohort of 16 who took part in the study, which is published in the journal Science Translational Medicine.