Researchers conducted a 20-year follow-up on the long-term benefits of hormone treatment for breast cancer.
The Karolinska Institutet in Sweden investigated the long-term benefits of hormone treatment for breast cancer in premenopausal women. The findings suggest that the hormone treatment provides protection after a long period and that different patients respond differently to treatments.
Hormone treatments have been used after tumour surgery to reduce the risk of breast cancer cells spreading, but it is unknown how long hormone treatment for breast cancer provides protection.
The findings were published in the Journal of Clinical Oncology.
The importance of hormone treatment for breast cancer
Around 80% of breast cancer cases are hormone-driven estrogen receptor-positive breast cancer, meaning the estrogen stimulates cells to divide, and the tumour will grow. As many women are diagnosed with this cancer at a young age, the long-term effects of hormone treatment for breast cancer are crucial.
The researchers utilised data for their investigation from the previous clinical trial STO-5 conducted between 1990 and 1997. The original trial included 584 premenopausal women with hormone-driven estrogen receptor-positive breast cancer and a control group that did not receive any hormone treatment for breast cancer.
“We could see that after 20 years, the risk of developing distant metastatic disease, i.e. spreading to other organs, had decreased among women who had received hormonal treatment with the drugs tamoxifen or goserelin or a combination of both, compared to those who had not received any hormonal treatment”, said the study’s first author Annelie Johansson, a postdoctoral fellow at the Department of Oncology-Pathology, Karolinska Institutet.
Using modern technology to analyse tumours
In later years, the researchers analysed tumours from the previous STO-5 study using modern technology. An example of this was the team investigating various breast cancer markers, such as the estrogen receptor and the progesterone receptor, and the tumour gene expression using a gene-risk signature.
The signature measures the activity of 70 different genes, which are calculated into risk points. This technology predicts the future development of the tumour cells at an early stage and thus categorises the patients into low and high genomic risk.
“The tumours in patients with high genomic risk often have a higher cancer growth rate. Therefore, these patients have an earlier risk of relapse where more aggressive treatment is needed, such as with goserelin, which quickly and effectively reduces estrogen levels. Patients who have a less aggressive disease may, on the other hand, have a long-term risk of recurrence. In these cases, tamoxifen appears to offer better protection”, commented Annelie Johansson.
The study is relatively small, but highlights the importance of individualised hormone treatment for breast cancer. For some patients, more aggressive treatment may be necessary for survival, yet milder hormone treatment for breast cancer may be appropriate for others, reducing side effects and improving quality of life. Further studies are required before any major changes to treatment recommendations.
“In order to further understand the long-term risk, treatment benefit and differences relating to age, we will now apply machine learning methods for image analysis of breast cancer tumours to further investigate the differences between tumours”, said Linda Lindström, research group leader at the same department and the study’s corresponding author.