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.
Professor Ian Ellis, from the University of Nottingham's division of cancer and stem cells, who worked on the test, said: "Using a panel of 10 biomarkers and other clinical information, we are able to categorise women with breast cancer into one of seven treatment-specific classes based on their personal cancer biology.
"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.
"In addition, the ability to give survival prediction will be welcomed by concerned patients. Decisions can be made more quickly, reducing waiting times and unnecessary consultation time."
Prof Ellis said the technology required to measure protein biomarkers in tumour samples is already in place in most pathology laboratories across the UK.
The test, described in the British Journal of Cancer, was developed using more than 1,000 breast cancer samples.
The research was funded by the Medical Research Council and involved the Nottingham University Hospitals NHS Trust and Nottingham Trent University's John van Geest Cancer Research Centre.
Jackie Harris, clinical nurse specialist at Breast Cancer Care, said: "Breast cancer is the most commonly diagnosed cancer in women in the UK and making decisions around benefits of certain treatments can often be difficult and stressful for patients.
"The Nottingham Prognostic Index Plus test will highlight an individual's risk and could be a useful tool to help patients to make these treatment decisions.
"This test is another step forward in helping to target and tailor treatment according to individual need. We look forward to hearing more about the progress of the test and when it will become available."