The test is being developed at Llanelli's Prince Phillip Hospital with the help of Singleton Oncology and the University of Swansea.
During recent trials, nearly half of patients who were initially recommended for chemotherapy and endocrine therapy, had their treatment changed to endocrine therapy alone.
This test will have a major impact on the lives of many women, allowing them to get on with their lives following breast cancer surgery rather than having to go through four months of chemotherapy."
The 'Oncotype DX' test, which is only for women with early breast cancer, will give clinicians a clearer idea of the risk and benefit of chemotherapy.
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South Wales Police tweeted in the early hours of Sunday morning that they had been caught on a stretch of the M4 near Port Talbot.
Cloudy and damp for most of us with outbreaks of rain.
More than 200 people attended the service after Bethel Community Church was destroyed by the fire.