Most women with early stage hormone receptor positive breast cancer do not benefit from chemotherapy on top of endocrine therapy after surgery if tests show they have a mid-range risk of recurrence, a large randomised trial has reported.1
“Half of all breast cancers are hormone receptor positive, HER2 negative, and axillary node negative. Our study shows that chemotherapy may be avoided in about 70% of these women when its use is guided by the 21 gene recurrence score, so limiting chemotherapy to the 30% who we can predict will benefit from it,” said lead author Joseph Sparano, from the Albert Einstein Cancer Center and Montefiore Health System in New York.
The study, funded by the US National Cancer Institute, was the largest breast cancer treatment trial ever conducted and included 10 273 women with hormone receptor positive, HER2 negative, axillary node negative, early stage breast cancer. Of the 9719 patients with follow-up information, more than two thirds (69%) had a mid-range score of 11 to 25 when tested with a widely used 21 tumour gene expression assay (Oncotype DX). These women were randomised to treatment with chemotherapy plus endocrine therapy or to endocrine therapy alone.
Results showed similarly high, disease free, survival rates in women treated with endocrine therapy alone as in those given chemotherapy in addition to endocrine therapy. At nine years, 83.3% of patients treated with endocrine therapy alone were free from breast cancer compared with 84.3% of those who were also treated with chemotherapy. The two groups also had similar rates of freedom from disease recurrence at a distant site (94.5% v 95.0%) and overall survival (93.9% v 93.8).
Further analysis showed an interaction between age and risk of recurrence. Women aged 50 years and younger and with a risk score of 16 to 25 were more likely to benefit from the addition of chemotherapy than others (P=0.004). This range of scores was found in 46% of women in this age group.
“This study will transform care immediately and for the better. These data provide critical reassurance to doctors and patients that they can use genomic information to make better treatment decisions in women with early stage breast cancer,” said Harold Burstein following presentation of the results at the American Society of Clinical Oncology annual meeting in Chicago on 3 June.
He added, “These are very important data because in this common cancer the most challenging decision is whether or not to give chemotherapy, with all the potential side effects. The vast majority of women who undergo this test on their tumour can be told they don’t need chemotherapy, with confidence.”
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