Improved Outcomes For Postmenopausal Women With Hormone Receptor Positive Early Breast Cancer

A case study of successful industry and university engagement

Summary

  • Breast Cancer is the most common type of cancer in women and the most frequent cause of cancer-related deaths.  Approximately 75% of all breast cancers in developed countries occur in postmenopausal women and 80% of these cancers are hormone receptor positive.
  • Conventional treatment of hormone receptor positive breast cancer involves the use of the endocrine therapy, tamoxifen.  However, tamoxifen increases the risk of endometrial cancer and blood clotting disorders.
  • An antioestrogen (aromatase inhibitor or AI) called anastrozole was investigated as an alternative to the use of tamoxifen.
  • Women on the study who received anastrozole for five years after surgery had a 24% lower risk of cancer recurrence than those women who received five years of tamoxifen. 
  • These results led to the registration of anastrozole for the treatment of early breast cancer in most countries.  It is registered and subsidised on the PBS and is the standard of care for postmenopausal women, with an excess of one million women impacted by this research.
  • Recently 10 years of tamoxifen treatment has been shown to be superior to five years. Further  five years of tamoxifen has been shown to prevent breast cancer in women at increased risk.

New Treatments For Hormone Receptor Positive Breast Cancer In Postmenopausal Women

John ForbesBreast Cancer is the most frequent cause of cancer-related deaths in women and also the most common type of cancer in women.  Approximately 75% of breast cancer cases in the developed world occur in postmenopausal women and around 80% of these cancers are hormone receptor positive. 

Prior to the ground breaking international Arimidex (anastrozole), Tamoxifen, Alone or in Combination (ATAC) study led in Australia by the Australia and New Zealand Breast Cancer Trials Group  (ANZBCTG), the standard of care for post-menopausal women with hormone receptor positive breast cancer was an antioestrogen drug called tamoxifen. 

While tamoxifen results in a reduction in tumour recurrence and mortality it also increases the risk of endometrial cancer and blood clotting disorders. 

The ANZBCTG ATAC study investigated the use of an alternative antioestrogen, an aromatase inhibitor (AI) called anastrozole to compare outcomes with those achieved through the use of tamoxifen.

A number of clinical trials confirmed that AIs offer significant efficacy and tolerability advantages over tamoxifen during the treatment phase. 

The result of the ANZBCTG study is that AIs, particularly anastrozole, have been proven as adjuvant treatment for postmenopausal women with hormone receptor positive early breast cancer. Women who received anastrozole for five years after surgery had a 24% lower risk of cancer recurrence than those women who received five years of tamoxifen. 

The results of this study have led to the registration of anastrozole for the treatment of early breast cancer in most countries. Anastrozole is now registered and subsidised on the Australian PBS and AIs are the standard of care for postmenopausal women with hormone sensitive breast cancer. 

Clinicians now have a range of strategies to treat postmenopausal patients with hormone sensitive breast cancer due to the results of AI trials such as ATAC. Treatment choices can now be based on patient preference and the side effect profile of available hormone therapies. The ability of AIs to lower the risk of cancer recurrence has resulted in fewer women requiring further health treatment for a cancer recurrence, meaning better health outcomes for women and, subsequently, significant savings in health budgets.

More recently it has been shown that larger duration therapy with tamoxifen for 10 years is superior to five years and tamoxifen has been shown to prevent breast cancer in women at increased risk.

Further Information

For further information regarding Optimisation, please visit the ANZBCTG website.  

For further information regarding collaborative engagement with the University of Newcastle and its researchers, please contact the Research Development Team.