Drugs that prevent the development of treatment-resistant prostate cancer may be in prospect following the discovery of a new protein.
The molecule, GPR158, is linked to a biological process that plays a critical role in the way the disease stops responding to standard hormone therapies.
Patients with raised levels of the protein were more likely to experience a recurrence of prostate cancer, said scientists.
They believe GPR158 could provide a target for new prostate cancer drugs.
It was discovered fortuitously while researchers were searching for new drug targets for the eye disease glaucoma.
Each year around 40,000 men are diagnosed with prostate cancer in the UK and 10,000 die from the disease.
Dr Matthew Hobbs of Prostate Cancer UK said: "Working out why the disease stops responding to treatment over time is one of the big unanswered questions.
"Finding these answers could hold the key to developing new treatments to save thousands of men dying every year."