A test which determines whether chemotherapy will benefit certain women with early-stage breast cancer has proven successful in Ireland.

Around 2,700 new cases of breast cancer are diagnosed in Ireland every year and it is acknowledged that the criteria currently used to decide whether chemotherapy is appropriate may result in overtreatment. In other words, women may receive chemotherapy even if it will not actually treat their disease.

In 2011, Ireland became the first European country to publicly fund the Oncotype DX breast cancer test.

Now, the findings of a major observational study carried out in Ireland have been presented at a major breast cancer conference in Austria. It was carried out to determine both the clinical and financial impact of the test during the first 18 months after it was made publicly available.

The researchers found that among 583 patients with node-negative breast cancer, 345 - that is 59% - underwent a change in their treatment.

Of these 345 patients, 339 patients who would previously have been recommended chemotherapy were changed to hormone therapy alone after the test revealed that they were likely to derive minimal or zero benefit from chemo.

Meanwhile, six patients who would not have been advised to undergo chemotherapy were recommended to get it following the test.

As the test is performed on a small amount of the tissue removed during your original surgery - whether this was a biopsy, lumpectomy or mastectomy - no additional surgery is required to undergo the test.

Aside from the benefits to women who did not have to undergo chemotherapy that was unlikely to help them, the test also saved the HSE around €800,000.

"The HSE was the first public health care system to reimburse this test in Europe. The results from Ireland demonstrate not only the impact of the personalised information Oncotype DX provides on treatment decisions, but also the significant cost savings associated with the use of the test over time," commented lead researcher, Dr Janice Walshe, a consultant medical oncologist at St Vincent's University Hospital in Dublin.

She led the research for the All Ireland Co-Operative Oncology Research Group (ICORG) in collaboration with the National Cancer Control Programme (NCCP).

The test was developed by Genomic Health and these findings, along with results from 11 other studies on the test, were presented at the 14th St. Gallen Breast Cancer Conference in Vienna.