WHAT IS ENDOCRINE (HORMONE) THERAPY FOR BREAST CANCER?

Hormone-Blocking Therapy

You may have heard of endocrine therapy or hormone therapy, but what is it exactly? How does it help people facing breast cancer and how is it different from hormone replacement therapy? Read on for an overview of what to expect from hormone therapy for breast cancer including its side effects, benefits and drawbacks and more.

What is it?

Endocrine therapy, otherwise known as hormone-blocking therapy, is a group of medications specifically designed to treat hormone receptor-positive breast cancer – i.e. tumours that are sensitive to oestrogen and/or progesterone. 

These therapies play a vital role in helping to shrink or slow the growth of cancer, ultimately improving a patient’s prognosis. Tamoxifen, a highly regarded and effective medication, is a shining example of the success of hormone therapy for breast cancer. 

The groundbreaking work of Breast Cancer Trials (BCT) in demonstrating the effectiveness of Tamoxifen has changed the course of breast cancer treatment for the better. In addition to Tamoxifen, other medications such as aromatase inhibitors (including anastrozole, letrozole, and exemestane) have been proven effective through BCT’s research.

How does hormone-blocking therapy work?

These drugs work by reducing oestrogen production, further contributing to the wide array of treatment options available for those battling hormone receptor-positive breast cancer. By continually working to advance endocrine therapy, trials offer hope and improved outcomes for patients facing this challenging journey.

A note on hormone replacement therapy

Often people mix up hormone-blocking therapy with hormone replacement therapy, but they are two very different things. In fact, they’re basically polar opposites. 

Endocrine (or hormone-blocking) therapy is used to block how hormones work to treat breast cancer, while hormone replacement therapy (HRT) is used to manage the symptoms of menopause. 

HRT is also commonly referred to as menopausal hormonal therapy (MHT). While there have been indications that certain types of HRT may increase the risk of breast cancer, it is still occasionally prescribed for a limited duration to women who are experiencing severe menopausal symptoms.

Types of Hormone Therapy for Breast Cancer

Blocking Oestrogen Production: Aromatase Inhibitors

Aromatase inhibitors play a significant role in reducing oestrogen production in postmenopausal women. This is an important consideration, as oestrogen can stimulate the growth of certain types of breast cancers. By effectively decreasing oestrogen levels, aromatase inhibitors help to control and mitigate the progression of hormone receptor-positive breast cancer.

Suppressing Ovarian Function

For premenopausal women, an alternative approach to hormone therapy involves suppressing ovarian function, which is the process of stopping the ovaries from producing oestrogen. Ovarian suppression, which can be achieved through medications or surgeries, may be recommended as an additional treatment for certain patients, providing them with an extra line of defence against breast cancer.

What is the best endocrine (hormone) therapy for breast cancer?

There is no one-size-fits-all answer to this question, as the optimal endocrine therapy depends on each individual’s unique circumstances. 

Treatment strategies vary, and patients may begin with one approach before switching to another based on side effects or other factors. 

Some may prioritise treatments that offer the greatest reduction in breast cancer recurrence risk, while others might seek a balance between risk reduction and minimising side effects. Ultimately, it’s crucial to have an open dialogue with your doctor and treatment team to weigh the pros and cons of available options and determine the best course of action for your specific situation.

What about men?

Men with hormone receptor positive breast cancer can definitely benefit from hormone blocking therapies. Much like with women, tamoxifen is the most commonly used option. However, your doctor may prescribe an injection such as goserelin to be used in conjunction with an aromatase inhibitor.

What you need to know about Endocrine (Hormonal) Therapy for Breast Cancer

Why have hormonal therapy?

Hormonal therapy is an essential component of breast cancer treatment, as it can slow or stop the growth of hormone-sensitive tumours. For those diagnosed with early-stage breast cancer, hormonal therapy helps prevent cancer recurrence, while for individuals with metastatic or advanced breast cancer, it reduces the impact of cancer in the breast and other affected areas.

Studies have shown that women with early-stage hormone receptor-positive breast cancer who receive adjuvant therapy for at least five years following surgery experience lower chances of cancer recurrence and a decreased mortality risk for up to 15 years post-diagnosis.

What does endocrine (hormone) therapy do for breast cancer?

Endocrine therapy works by depriving breast cancer cells of the hormones they need to grow and multiply, effectively stalling or eliminating the cancer. This targeted approach has proven to be highly effective in treating hormone-sensitive breast cancer, as it addresses the underlying factors that contribute to cancer growth and progression.

When should you start endocrine (hormone) therapy?

It really all depends on your individual situation and what is recommended by your doctor

Before surgery or chemotherapy:

In some cases, it may be administered before  surgery as neoadjuvant therapy to shrink the tumour, making it easier to remove surgically.

After surgery or chemotherapy:

Hormonal therapy is often used after surgery, and if necessary, after chemotherapy or radiotherapy, as adjuvant therapy to help reduce the risk of cancer returning.

How long should hormone therapy be taken for?

The duration of hormone therapy depends on various factors, but doctors typically recommend daily medication for at least five years after completing treatments like surgery, chemotherapy, and/or radiotherapy. This extended course of therapy helps reduce the risk of cancer returning and improves overall outcomes. 

However, based on the likelihood of cancer recurrence, potential benefits, and side effects experienced, a longer treatment period of seven to eight or even 10 years might be suggested.

Hormone therapy for metastatic and stage 4 breast cancer

For patients with metastatic or recurrent hormone-sensitive breast cancer, hormone therapy is an effective treatment option. It is also appropriate for ER-positive breast cancer that has recurred in the breast, chest wall, or nearby lymph nodes. All previously mentioned endocrine therapies can be used for the treatment of metastatic breast cancer and they may be combined with other medications, such as a CDK4/6 inhibitor (palbociclib, ribociclib, or abemaciclib), to enhance the efficacy of the endocrine therapy.

What are the Side Effects of Hormonal Therapy?

Hormonal therapy can cause some people to experience:

• Menopausal symptoms such as hot flushes, night sweats, weight gain, mood swings and reduced libido 
• Anxiety 
• Sleep disturbance 
• Muscle and joint pain
• Leg cramps
• Fatigue

There are a range of other less common side effects that you can discuss with your treatment team. Like with any treatment, with hormone treatment for breast cancer it is important to remember that there are strategies available to manage the side effects and improve your experience.

What are the pros and cons of endocrine (hormone) therapy for breast cancer?

Pros of hormonal therapy for breast cancer

Hormonal therapy offers several advantages in the treatment of breast cancer. 

• It helps reduce the risk of cancer recurrence in people with early-stage breast cancer.
• It’s easy to administer, typically taken as an oral pill or, in some cases, a monthly injection.
• It helps improve survival rates.

Cons of hormonal therapy for breast cancer

On the other hand, hormone therapy does have some downsides. 

• Certain forms may not be effective for premenopausal women. 
• Common side effects can include hot flushes, changes in the menstrual cycle, mood swings, night sweats, reduced bone density, and a lowered sexual drive.
• In rare cases and with specific treatments, patients may experience side effects such as blood clots, thickening of the uterine lining (including rare cases of endometrial cancer), and cataracts. 

However, it’s important to note that the benefits of endocrine therapies, in terms of reducing breast cancer risk, typically far outweigh these risks.

Hopefully, this gives you a quick overview of how hormonal therapy can play a vital role in the treatment and management of hormone receptor-positive breast cancer. 

While there are different types of hormone therapy, it is important to remember that each individual’s situation is unique, and the optimal course of treatment should be determined through open dialogue with your healthcare team. 

At Breast Cancer Trials, with the help of our donors, we’re always working to improve treatments and advance research. Together, we can build a brighter future for breast cancer patients with better and better treatments. Find out how your donation can help advance breast cancer treatment here.