A genetic test that predicts how well chemotherapy and drugs will work in individual cancer patients is being developed by scientists.
According to creators, the revolutionary test will allow doctors to prescribe drugs only to those people who are likely to benefit from the medicines rather than giving them to a wide range of patients in the knowledge that only some individuals will respond to the treatment.
The way by which it could be differentiated between patients who are "responders" and "non-responders" to drugs is seen as one of the most important developments in modern medicine, reports The Independent.
"Personalized" treatment based on the analysis of a person's DNA is considered one of the key achievements that will emerge from the decoding of the human genome.
Starting with 829 genes in breast cancer cells, in the latest study the team whittled down the possibilities to six genes which had an impact on whether a drug worked.
They then showed that these genes could be used to predict the effectiveness of a drug called paclitaxel in patients.
It is hoped the approach, reported in The Lancet Oncology, can be replicated for other cancers and treatments.
The international project, including researchers from Cancer Research UK's London Research Institute, opens the way for breast cancer treatment to be targeted to those who will benefit the most.
The new test will be able to identify patients with any of the six faulty genes so that they could be spared the ordeal of being given paclitaxel, which can cause side-effects including immune suppression and nausea.
"A great challenge in cancer medicine is determining which patients will benefit from particular drugs and it is hoped that this research is a step towards more rapid developments in this type of personalized medicine," said Dr Charles Swanton, head of translational cancer therapeutics at Cancer Research UK.