Approximately two-thirds of breast cancers have hormone (oestrogen and / or progesterone) receptors on the cancer cell surface, which help them grow. A laboratory test on the breast cancer tissue will identify if the breast cancer is hormone receptor positive (also known as ER and / or PgR positive).
Hormone receptor positive breast cancers are sensitive to hormone (also known as ‘endocrine’) treatments.
If your breast cancer is hormone receptor negative, hormone treatments will not be of benefit to you.
Hormone therapy can be given:
- Before surgery (also known as neoadjuvant treatment): To shrink a cancer (and possibly make it operable).
- Instead of surgery: In patients who are not fit enough for an operation.
- After surgery (also known as adjuvant treatment): Post-operative hormone therapy reduces the risk of breast cancer recurrence (by about one third) and also reduces the chances of developing a cancer in the other breast (by about 40%).
- To treat secondary breast cancer (cancer which has spread to other parts of the body): Hormone treatments can help control secondary breast cancer and therefore improve symptoms the breast cancer causes.
Types of hormone therapy:
The choice of hormone drug given depends on whether you have gone through the menopause or not.
Drugs that block oestrogen:
- Tamoxifen: Tamoxifen blocks oestrogen binding to receptors on breast cancer cells and therefore stops cancer cell growth. It works in patients before or after the menopause. Tamoxifen is a tablet taken daily for between 2 – 10 years.
- Fulvestrant (Faslodex®): Fulvestrant is an injection which blocks and damages oestrogen receptors. It can be used to treat secondary breast cancer after other hormone drugs have stopped working.
Drugs which lower oestrogen levels:
Aromatase inhibitors (AIs)
These are tablets which inhibit an enzyme called aromatase and therefore stop the production of oestrogen in the adrenal glands and fat cells. They are only effective in ladies who have gone through the menopause.
Three different AI tablets are available:
Drugs which switch the ovaries off:
Sometimes, stopping the ovaries working and producing oestrogen can be helpful in ladies who have not gone through the menopause.
Luteinizing hormone-releasing hormone (LHRH) drugs
These drugs stop a signal sent from the brain to the ovaries to make oestrogen.
They are given as an injection into the tummy wall, every 4 weeks.
Sequencing of hormone treatments:
Hormone treatments can be given in different sequences, depending on the type of cancer and whether the ovaries are still working.
- Tamoxifen for 10 years
- Tamoxifen for 2-3 years, followed by an AI to complete 5 years treatment
- Tamoxifen for 5 years, followed by an AI for 5 years
- An AI for at least 5 years
The preferred sequence will be discussed with you.
These tablets enhance the effectiveness of hormone therapy drugs for secondary breast cancer when given in combination with aromatase inhibitor tablets or fulvestrant injections.