Almost half of women with the most common form of early breast cancer could be spared chemotherapy as a result of a genetic test, research suggests.
The Oncotype DX test involves the examination of genes taken from a sample of a tumour removed during surgery.
It can help doctors decide whether chemotherapy would actually benefit patients and the risk of cancer returning.
Research which was carried out by Simon Holt, a breast surgeon at the Hywel Dda Health Board in Wales, found that 46 per cent of patients with early stage disease could be spared unnecessary chemotherapy.
The 142 NHS patients in his study had oestrogen receptor positive breast cancer, the most common type, and had initially been offered chemotherapy and hormone therapy.
The Oncotype DX test is currently being reviewed by the National Institute for Health and Clinical Excellence (Nice).
This could lead to its widespread use on the NHS.
Mr Holt said: “With nearly 50,000 women diagnosed with early stage breast cancer each year in the UK, a genomic test like Oncotype DX that is capable of predicting treatment benefits and/or outcomes could have an important role to play in improving treatment decision making and ultimately impacting on quality of care.
“The Oncotype DX test allows us to use our health funds more effectively while at the same time, sparing patients from unnecessary chemotherapy.”
Mr Holt presented his findings at the San Antonio Breast Cancer Symposium last week.