US scientists have designed a genetic test which could predict how a patient with breast cancer responds to chemotherapy. Researchers say the test, which works for those with certain newly diagnosed forms of cancer, could help women avoid unnecessary chemotherapy.

‘For some patients it would provide an affirmation that chemotherapy would really help them. For others, the results may suggest a less robust response to chemotherapy', said Professor Fraser Symmans, of the University of Texas and lead author of the study.

The study spanned ten years and enrolled 310 women undergoing chemotherapy for invasive HER2 negative - Herceptin unresponsive breast cancer. The women were tested for resistance to chemotherapy and then after three years the researchers assessed patient survival and tested their DNA for genetic markers, which could be correlated to their treatment response.

The team identified  genetic markers, which it believed could predict whether the cancer would respond to hormone therapy or whether the cancer would be resistant to chemotherapy. The genetic marker screen was then used on 198 new patients to see if it could predict the outcome of treatment.

Of the women the test predicted would respond to chemotherapy, 92 percent survived three years without a relapse. They represented an 18 percent lower risk of death compared to those the test identified chemotherapy as an unsuitable course of treatment.

'This result doesn't necessarily mean women should abandon chemotherapy completely, but that they perhaps should consider an additional or alternative treatment', said Professor Symmans.

While the team admits the results are still preliminary, it believes it could be another step towards personalised treatment. Some remain skeptical, however. The test, while promising, is 'not ready for patients', stated Professor Massimo Cristofanilli, chairman of medical oncology at Fox Chase Cancer Center in Philadelphia. Nor does it predict which therapy will be best, he added.

The test was developed jointly by researchers at MD Anderson Cancer Centre, University of Texas, and Nuvera Biosciences in Massachusetts. The study was published in the Journal of the American Medical Association.