"Scientists have developed an improved test to predict how long women with breast cancer may live and which treatments may work.
Some doctors in the UK use a formula called the Nottingham Prognostic Index (NPI) to give them an idea of a patient's outlook, based on the size of the cancer, whether it has spread to the lymph nodes and how advanced the disease is.
While experts stress it is not possible to predict exactly what will happen in each individual case, the index can give a general prognosis.
The NPI was developed more than 30 years ago and so experts have now developed an updated test based on the latest evidence.
They said the new Nottingham Prognostic Index Plus (NPI+) includes even more biomarkers of the disease and could be available to patients within two years.
"We believe the categorisation of women with breast cancer into more specific risk classes will deliver better targeting of relevant therapies, which will result in improved outcomes with reduced costs and less anxiety for the patient.
"NPI+ will reduce uncertainty for clinicians and patients by removing a large number of patients with indeterminate prognosis and allow better-informed treatment decisions.