Tens of thousands of breast cancer patients could be saved from undergoing gruelling chemotherapy with a new test which shows whether drugs will be effective.

Many women with early stage breast cancer get no benefit from chemotherapy after having surgery and radiotherapy but some still receive treatment to be on the safe side.

Now a new test which screens for 70 genetic variants which increase the risk of cancer returning, has found to be effective at predicting which patients can be spared treatment.

Results showed that around 46 per cent of women with newly diagnosed early-stage breast cancer were classified as low risk by the test, called MammaPrint, and did not need medication.