It has emerged that a potentially life-saving breakthrough by British scientists could pave the way to overcoming breast cancer resistance to hormone treatments.
And scientists at the Institute of Cancer Research in London believe the same discovery may also have implications for prostate cancer in men.
Three quarters of breast tumours are fuelled by the female hormones oestrogen and progesterone, and drugs such as tamoxifen, which target hormone sensitivity, can stop tumours growing.
However, sometimes a patient develops resistance and the drug ceases to work.
But the researchers have now identified a protein that appears to be critical to resistance to tamoxifen.
Patients with low levels of the protein, cyclin-dependent kinase 10 (CDK10), in their tumours were less likely to benefit from the drug, the researchers found.
Their cancers were more likely to return, and they tended not to survive for as long as women who had naturally higher levels of the molecule.
The new research, published in the journal Cancer Cell, opens the door to ways of identifying women most likely to benefit from tamoxifen at an early stage. Those who are expected to become resistant could then be given a different therapy more suited to them.