Protein boost 'slows' breast cancer cases.
THOUSANDS of breast cancer patients could benefit from a protein that slows tumour growth.
Experts said half of 50,000 cases diagnosed every year in the UK could be improved with progesterone.
Dr Jason Carroll, of the Cancer Research UK Cambridge Institute, said: "We've used cutting-edge technology to tease out the role progesterone receptors play in breast cancer - a mystery that has baffled scientists for many years."
He called for clinical trials on what could be a cheap and effective treatment.
Oestrogen-sensitive breast cancers are commonly treated with drugs such as Tamoxifen, which could be combined with progesterone to mount a dual attack.