The initial results of an international breast cancer clinical trial provides evidence that a genetic test is able to reliably identify a subgroup of women with early stage, hormone receptor positive breast cancer who can safely avoid chemotherapy.

Many women who are diagnosed with hormone-receptor positive breast cancer are adequately treated with hormone treatment alone and may not need the addition of chemotherapy. The decision to include chemotherapy as part of a patient’s treatment is largely based on the characteristics of the tumour’s pathology and size. However, there is currently no effective way to determine which women could safely avoid chemotherapy and avoid the side effects associated with this treatment.

The TAILORx clinical trial assessed the effectiveness of a genetic test called Oncotype DX®, to more accurately determine which patients are likely to benefit from chemotherapy and those who won’t. The test searches for the presence of 21 breast cancer related genes in breast tissue and produces a Recurrence Score® that predicts the risk of breast cancer recurrence. The score ranges from 0-100 and the higher the score, the greater the chance that breast cancer will return. In TAILORx, women with a Recurrence Score of 10 or less received hormone therapy alone; women with a Recurrence Score of greater than 25 received hormone therapy plus chemotherapy; and those with a mid-range Recurrence Score from 11-25 were randomised to receive hormone therapy with or without chemotherapy.

This analysis involved the group of 1,626 patients with a Recurrence Score between 0 and 10, and found that 99% of women with hormone receptor positive, HER-2 negative, node negative breast cancer were free of recurrence after five years of hormone therapy alone. Outcomes were excellent, irrespective of patient age at diagnosis, tumour size and tumour grade. Furthermore, the rate of invasive disease-free survival in this population at 5 years was almost 94%, while the risk of cancer returning at a distant site was less than 1%.
The study was coordinated by the ECOG-ACRIN Cancer Research Group in the United States and was conducted in Australia and New Zealand by the Australia and New Zealand Breast Cancer Trials Group (ANZBCTG). More than 10,200 women participated in the study worldwide including 25 women from 10 institutions in Australia and New Zealand. The initial results of TAILORx were published in the New England Journal of Medicine.

Professor Bruce Mann, ANZBCTG Board Member and member of the ANZBCTG’s Scientific Advisory Committee, says “early results from TAILORx shows that the Oncotype DX assay can provide women with early stage breast cancer and a low recurrence score, greater certainty that hormone therapy alone is sufficient and they can avoid the side effects of chemotherapy which provides no additional benefit to their treatment. TAILORx provides evidence that women in the future may effectively use hormonal therapy alone if the Recurrence Score is 10 or less.”

“This study is ongoing and will evaluate whether those with a mid-range recurrence score can also safely avoid chemotherapy. Previous research has already shown the benefits of chemotherapy for those in the high recurrence score range.”

The ANZBCTG is the largest, independent oncology clinical trials research group in Australia and New Zealand and for more than 35 years, has conducted a national clinical trials research program for the treatment, prevention and cure of breast cancer. The research program involves more than 700 members at 87 leading medical institutions in Australia and New Zealand. The ANZBCTG’s fundraising department is the Breast Cancer Institute of Australia. More information about the ANZBCTG and its research program is available at www.anzbctg.org.

Oncotype, Oncotype DX, Recurrence Score, are trademarks or registered trademarks of Genomic Health, Inc.