An Irish-led study has provided a clearer insight into the role that hormones play in the development of breast cancer. It is hoped these findings could enhance treatment for the disease and improve overall survival rates for patients.

Around 3,600 women are newly diagnosed with breast cancer every year in Ireland, while in 2020 alone, 2.3 million women were diagnosed worldwide.

The hormone oestrogen has been shown to have an impact on breast cancer development and there is strong evidence that other hormones, such as androgens, may also play a role.

Patients can respond differently to hormone therapy, with some having a more positive response than others.

“Hormones are powerful signalling molecules that play important roles in helping our bodies function normally and respond to the world around us. For over 100 years, we have known that oestrogens play a role in making breast cancers grow and many of the common drugs prescribed to treat it aim to reduce the amount of these hormones or to block their action.

“Unfortunately, not all patients will respond to these drugs and we need a better way to determine response to this type of therapy,”  explained the study’s senior author, Dr Marie McIlroy, a lecturer in endocrine oncology research at the RCSI University of Medicine and Health Sciences.

Researchers from the RCSI analysed patients’ hormone profiles in order to gain a deeper understanding of how breast cancer cells are affected by different hormones and why patients respond differently to hormone therapy.

They found that hormone profiles before and after treatment play a significant role in the success of hormone therapy. This finding opens the door to further studies in larger patient cohorts, which could improve success rates in breast cancer treatment.

“By looking at each individual person’s tumour hormone levels, we get a better idea of the differences between people who respond well to hormone treatment and those who do not, potentially enabling us to make more informed decisions on treatment options for patients,” Dr McIlroy said.

The study was carried out in collaboration with researchers from the Institute of Genetics and Cancer at the University of Edinburgh Cancer Research Centre; Manchester University, NHS Foundation Trust; the department of pathology at Beaumont Hospital in Dublin and Charles University in the Czech Republic.

It is published in the journal, Clinical Cancer Research, and can be viewed here.