Extended treatment may prevent breast cancer returning for some women

Women with breast cancer receiving further treatment with an aromatase inhibitor, which reduces the production of oestrogen, may prevent breast cancer from returning.


The results of the ANZ 0501 LATER clinical trial were announced at the American Society of Clinical Oncology (ASCO) Annual Meeting, in Chicago USA. The trial was developed by Australian researchers, Professor John Forbes AM and Professor Michael Green, and coordinated by the Australia and New Zealand Breast Cancer Trials Group (ANZBCTG).


Hormone receptor positive breast cancer is the most common type diagnosed in the 15,000 Australian women expected to be diagnosed this year. Many postmenopausal women who have been treated for hormone receptor positive early stage breast cancer are at risk of either their breast cancer returning or a new primary breast cancer diagnosis. At least half of recurrences happen more than five years after the initial diagnosis.


Aromatase inhibitors reduce the production of oestrogen in postmenopausal women, so less oestrogen is available to stimulate the growth of breast cancer cells.


The LATER clinical trial examined whether additional treatment with an aromatase inhibitor called letrozole, commenced much later after the initial diagnosis of breast cancer, could reduce the risk of breast cancer returning in this large group of women. 360 women participated in the LATER study.


ANZBCTG Clinical Fellow, Dr Nicholas Zdenkowski, presented the results of the LATER study at ASCO. He said it is the first time that a randomised trial has shown that reintroducing an aromatase inhibitor is beneficial, after a break of one year or more, and in some cases a much longer break.


This is the first clinical trial showing that an aromatase inhibitor after any standard adjuvant hormone therapy, not just the drug tamoxifen, prevents breast cancer recurrence,” said Dr Zdenkowski.


The results are supportive of longer hormone therapy being useful for some women with hormone receptor positive breast cancer. We now need to know which patients are most likely to benefit from extended adjuvant endocrine (hormone) therapy.


On behalf of the research team, I would like to thank the women who were enrolled in the study, and all investigators and site staff at participating institutions throughout Australia and New Zealand, who contributed to LATER. Collaboration is the key to clinical trial research and the development of improved treatment and prevention options for women at risk or diagnosed with breast cancer.”


The ANZBCTG is Australia’s national organisation dedicated entirely to breast cancer clinical trials research. It conducts a national clinical trials research program for the treatment, prevention and cure of breast cancer. The research program involves multicentre clinical trials and collaboration with more than 80 institutions and over 700 researchers throughout Australia and New Zealand.


More than 14,000 women have participated in ANZBCTG breast cancer clinical trials. The ANZBCTG’s fundraising department is the Breast Cancer Institute of Australia.


The ANZ 0501 LATER clinical trial received funding from the National Health and Medical Research Council and the Breast Cancer Institute of Australia. Novartis Australia Pty Ltd provided partial funding and the study drug.


30 May 2015.