Anti-hormone therapy for breast cancer

Some types of breast cancer need female reproductive hormones to survive and grow. These are known as hormone receptor-positive breast cancers, and they are divided into two types:

• ER-positive (ER+) breast cancer – cancer cells with hormone receptors for oestrogen
• PR-positive (PR+) breast cancer – cancer cells with hormone receptors for progesterone

Anti-hormone therapy works by using medication to block or reduce the interaction between cancer cells and hormones. This helps to slow down or stop the growth of hormone-dependent cancer cells. This is also known as endocrine therapy.  

Anti-hormone therapy works by:

• Blocking hormone receptors, which prevents hormones from attaching to cancer cells
• Limiting hormone production, which slows down the growth of hormone-dependent cancer cells

Depending on the type of breast cancer, your age, and whether you have reached menopause, treatment may consist of one or more medications. If you respond well to treatment and the risks and side effects are manageable, anti-hormone therapy can be continued for a period of five to ten years.  

Not every breast cancer patient needs anti-hormone therapy. It is only suitable for oestrogen-positive and/or progesterone-positive cancer. Your doctor will run routine tests – known as immunohistochemistry tests – on your cancer cells to find this out.

Anti-hormone therapy may be recommended:

• After surgery to reduce the risk of recurrence and metastasis  
• After chemotherapy for patients with a high risk of recurrence
• As the main treatment if the tumour is highly hormone-sensitive and surgery is not appropriate
• Before surgery or instead of chemotherapy in locally advanced postmenopausal breast cancer
• For several weeks before surgery to test hormone sensitivity

Anti-hormone drugs should not be taken during pregnancy. If you are pregnant or planning to have a baby, your doctor can help tailor your treatment accordingly.  

There are various possible treatment plans for anti-hormone therapy. They vary depending on the type and stage of cancer, your menopausal status, any treatments you have already had, and how well you tolerate the medicines.  

Your doctor will explain in detail what to expect from your individual treatment plan.  

How the treatment is administered

Anti-hormone therapy is usually administered daily in the form of a tablet. The number of tablets you take depends on how many medicines are prescribed in your treatment plan.  

Younger, premenopausal women may also require an injection every one to three months to suppress ovarian function. This is intended to limit oestrogen production in the ovaries.  

Duration of treatment

Anti-hormone therapy may be beneficial over a period of several years, depending on how the cancer responds to treatment and whether the side effects are manageable. You will have regular check-ups with your doctor to monitor your progress and well-being.  

The individual anti-hormone therapy drugs work in different ways. If your current treatment is not working well for you, your doctor may suggest a different drug.  

Effects on you

Every person responds differently to anti-hormone therapy. Many side effects can be alleviated by various measures, e.g. exercise, dietary changes, acupuncture. We will be happy to advise you on this matter.

Sometimes anti-hormone therapy can trigger the menopause. Your doctor and the nursing team will discuss fertility with you before you decide on treatment.

The most common side effects of anti-hormone therapy for breast cancer are menopausal symptoms:  

• Irregular or absent periods – this may be temporary or permanent
• Hot flushes
• Vaginal dryness
• Night sweats
• Mood changes
• Joint and muscle pains
• Reduced libido
• Osteoporosis (weak bones) – bone-modifying agents can help reduce the risk of bone fractures
• Increased risk of blood clots
• Weight gain  

If you notice any side effects, talk to your care team and your doctor. They will advise you on how to manage these symptoms or suggest a different medication instead.  

Hormone replacement therapy

Anti-hormone therapy should not be confused with hormone replacement therapy.  

• Anti-hormone therapy is a breast cancer treatment that often causes menopausal symptoms as a side effect.
• Hormone replacement therapy is a treatment that is often used to relieve menopausal symptoms.  

Hormone replacement therapy is not usually suitable for people who have already had breast cancer. However, other therapies are available to alleviate menopausal symptoms.