Scientists have identified six distinct classes of breast cancer that have different prognoses and that respond differently to chemotherapy.

The discovery will help doctors individualise treatments for the disease, the researchers said yesterday at the National Cancer Research Institute conference in Birmingham. The research team, led by Prof Ian Ellis from the University of Nottingham, took tissue samples from over 1,000 breast cancer patients and found that levels of certain cancer-related proteins differed between them.

By grouping cancers according to their protein levels, six distinct classes of breast cancer were identified. Two of the classes were found to be associated with longer survival rates, while one class showed survival rates significantly below the rest.

Only 60% of breast cancer cases were found to fit perfectly into one of the six classes, however, and the remaining 40% had mixed characteristics.

Nonetheless, one of the researchers, Dr Andy Green, said: "Classifying cases of breast cancer in this way has important implications for the future diagnosis and treatment of the disease." He added that "knowing what class of breast cancer a patient has will help doctors to decide on the best treatments specific to that patient – particularly as the trend towards customised therapeutics continues."

Dr Kat Arney, senior science information officer at Cancer Research UK, said: "Breast cancer is not just one disease, and different types of breast cancer need different treatments. In the future, this classification strategy may help doctors to make better decisions about how to treat women, so everyone gets the best possible therapy."

The findings are the result of a multi-disciplinary collaboration between scientists, doctors and other experts at the University of Nottingham, Nottingham University Hospitals NHS Trust, Nottingham Trent University, University of Milan and Liverpool John Moores University. By Michael Day