A faulty gene normally linked to breast and ovarian cancer may also increase the risk of prostate cancer in younger men, research has shown.

One in 100 men diagnosed with prostate cancer under the age of 65 has a mutant BRCA2 gene, according to the study.

Such patients could be prioritised for trials of new drugs called PARP inhibitors that target cancers linked to the mutations, say scientists.

Lead researcher Ros Eeles, professor at the Institute of Cancer Research in London, said: “Our study shows that men diagnosed with prostate cancer at a young age have a higher chance of carrying a faulty BRCA2 gene.

“With the arrival of PARP inhibiting drugs to target tumours with BRCA mutations, there may be benefits from routinely testing prostate cancer patients diagnosed before 65 for this gene fault.

“Prostate cancer patients with this gene fault also tend to have a poorer prognosis so we are also studying whether BRCA2 mutations are more common among patients with more aggressive disease.

“Ultimately, we hope to develop a full clinical picture of BRCA2-linked cancers, which will help us to work out the best way to treat these patients.”

The scientists analysed BRCA2 in blood samples of almost 2,000 prostate cancer patients. Each year around 36,000 men in the UK are diagnosed with prostate cancer and 10,000 die from the disease. About a quarter of cases are identified in men under the age of 65. Few men younger than 50 develop the disease. A faulty mutant version of BRCA2 was linked to an eight-fold increased risk of prostate cancer by the age of 65, the study found.

For the under-65s, having the mutation increased the risk of prostate cancer from just below two per cent to 15 per cent.

The findings were published in the British Journal of Cancer. Lesley Walker, director of cancer information at Cancer Research UK, which owns the journal, said: “Once gene testing becomes faster and cheaper, this study suggests that a new range of treatments could potentially open up for some prostate cancer patients.”