A new online tool has been developed that allows GPs to effectively calculate a patient's risk of developing breast cancer. The system is the first to combine a broad array of different elements, including genetics and environmental factors, to come up with a precise risk evaluation that could be used to customize screening timetables or prompt preventative therapies.

The online tool is called CanRisk and it is based on an algorithm called BOADICEA (the Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm). The system accounts for over 300 genetic risk factors, alongside family history and variables such as weight, alcohol consumption and age at menopause.

"This is the first time that anyone has combined so many elements into one breast cancer prediction tool," says Antonis Antoniou, from the University of Cambridge and lead author on the new study. "It could be a game changer for breast cancer because now we can identify large numbers of women with different levels of risk – not just women who are at high risk."

This ability to easily and precisely stratify patients into a variety of different risk groups is designed to help doctors better tailor individual care to patients, avoiding unnecessary screening for low-risk patients, or instituting preventative therapies for high-risk ones.

"This should help doctors to tailor the care they provide depending on their patients' level of risk," explains Antoniou. "For example, some women may need additional appointments with their doctor to discuss screening or prevention options and others may just need advice on their lifestyle and diet."

The CanRisk online tool is currently being tested and optimized by practice nurses and GPs before it is potentially rolled out into wider use, however, the algorithm is not without current limitations. As BOADICEA was developed using UK population data it is suggested the results may be reasonably accurate for similar Western populations, but most likely increasingly unreliable when evaluating Eastern or developing populations.

As with other gene-based health-risk evaluations the system is primarily designed to be used by clinicians to assist in consultations with patients. It is unclear how widely available the tool will be once it is completed but it is always recommended that these kinds of life-determining risk evaluations be conducted through GPs or primary healthcare practitioners.

"Although having an increased risk of breast cancer means a woman is more likely to develop the disease – it's by no means a certainty," explains Richard Roope, from Cancer Research UK. "A woman at high risk may never get breast cancer just as a woman at low risk still could. But any woman with concerns should speak to her GP to discuss the options."

The new study was published in the journal Genetics in Medicine.