Hormone Therapy for Breast Cancer: What to Know

Breast cancer is a condition that includes several subtypes, each with unique characteristics and treatments that are known to work best. One specific type of breast cancer is hormone receptor-positive (HR+) breast cancer. Hormone receptor-positive breast cancer cells bind to estrogen, progesterone, or both, which results in cancer growth.

Hormone therapy is one of the effective treatment options that either blocks or reduces the levels of estrogen and progesterone that the cancer cells need to grow. Although proven to be effective in slowing cancer growth and keeping cancer from recurring, there are some side effects that patients should understand and prepare for.

How Hormone Therapy Works for Breast Cancer

Breast cancers with estrogen receptors are classified as ER-positive (ER+), while those with progesterone receptors are known as PR-positive (PR+). ER-positive and PR-positive breast cancers can benefit from hormone therapy. Your biopsy report will provide information on whether the cancer has any of these characteristics. The majority of breast cancers are hormone-positive, so hormonal therapy will likely be discussed.

How Hormone Therapy is Used for Patients Who Are Pre and Post-Menopause

For premenopausal women, hormone therapy can prevent hormones from binding to cancer cells and/or suppress the ovaries' ability to produce estrogen. Your breast cancer doctor will carefully select hormone therapy treatments to minimize bone loss and other unwanted side effects. Ovarian suppression, whether achieved through surgery or medication, may result in early menopause. Patients are often advised to continue hormone suppression therapy for up to 10 years after treatment to lower the chance of the cancer returning.

In postmenopausal women, ovarian suppression is not needed. However, blocking estrogen production by fat cells is necessary.

There are typically some side effects of hormone therapy. Pre-menopausal women may have more noticeable effects because they have not yet experienced a reduced level of estrogen in their bodies.

Types of Breast Cancer Hormone Therapies

There are several types of hormone therapy, especially for hormone receptor-positive breast cancers. Three common approaches include:

• Blocking the effect of estrogen on breast cancer cells. This creates a barrier between hormones and cancer cells, slowing tumor growth and leading to the death of cancer cells. Medications that block hormones fall into two categories: selective estrogen receptor modulators (SERMs) and selective estrogen receptor degraders (SERDs). The hormone therapy recommended for each patient will be based on their menopause status and stage of cancer.
• Suppressing ovarian function in premenopausal women. Women who have not yet reached menopause may undergo ovarian ablation to reduce or eliminate estrogen production. This can be accomplished through surgery to remove the ovaries (oophorectomy) or with medications called luteinizing hormone-releasing hormone (LHRH) agonists. These may be used alone or in combination with other hormone therapies.
• Lowering hormone production in postmenopausal women. Although the ovaries no longer produce estrogen after menopause, body fat can still produce estrogen through the enzyme aromatase. Aromatase inhibitors (AIs) reduce post-menopausal estrogen levels, starving cancer cells of their necessary fuel.

When Do Breast Cancer Patients Receive Hormone Therapy?

You may be familiar with hormone therapy given after surgery to block the production of hormones for 5-10 years. This has proven to reduce the risk of cancer recurrence. Hormone therapy can also be used before surgery to help shrink the tumor for easy removal, called neoadjuvant therapy. It can also be used if breast cancer has recurred or spread after treatment is complete.

Hormone therapy may also be recommended for healthy women who are at a higher risk of breast cancer, including those with a family history of breast cancer or genetic mutations, such as BRCA1 and BRCA2.

The Pros and Cons of Breast Cancer Hormone Therapy

Hormone therapy comes with side effects, but the advantages often outweigh the disadvantages, making it a valuable treatment option for breast cancer. However, it’s important to be well-informed about what to expect so you can understand why the drug is included in your treatment plan and prepare for side effects.

Pros of Hormone Therapy for Breast Cancer

Some positive aspects of breast cancer hormone therapy include:

• Improved survival rates: Hormone therapy provides long-term benefits that are proven to enhance survival.
• Reduced recurrence risk: Hormone therapy is highly effective at preventing hormone-receptor-positive breast cancer from returning, reducing the likelihood of recurrence by at least 40% when taken as directed.
• Easy to administer: Hormone therapy medications are typically available in pill form, allowing patients to take them at home rather than undergoing infusion treatments.
• Non-cytotoxic: Unlike chemotherapy, which can damage or kill cells, hormone therapy targets hormone-sensitive breast cancer without the same harmful effects.
• Effective for metastatic cancer: This treatment can help control the growth and symptoms of advanced hormone receptor-positive breast cancers.

Cons of Hormone Therapy for Breast Cancer

Potential downsides to hormone therapy for breast cancer may include:

• Requires long-term use: The duration of hormone therapy varies among patients. On average, it can last anywhere from 5 to 10 years or longer, depending on individual circumstances.
• Side effects: Side effects vary from person to person and can last for an extended period due to the long-term use of hormone therapies. Some of the common side effects include hot flashes, mood swings, joint pain, vaginal dryness, and fatigue, although you may not experience all of these. Your oncologist can suggest different medications or adjust doses if side effects become challenging to manage.
• Risk of serious complications: Some patients may experience severe side effects, including blood clots and stroke. Postmenopausal women taking Tamoxifen have an increased risk of developing endometrial cancer.
• Bone density loss: Premenopausal women taking aromatase inhibitors can experience reduced bone density over time.
• Not effective for all breast cancers: Hormone therapy is effective only for specific subtypes of breast cancer. Hormone receptor-negative cancers do not benefit from this type of treatment.

Hormone Therapy for Breast Cancer in the Willamette Valley

At Willamette Valley Cancer Institute, we develop highly precise breast cancer treatment plans tailored to each patient and their unique diagnosis. Our breast cancer oncologists and surgeons are here to help you understand a diagnosis and take the next steps to recovery. We also offer second opinions regarding diagnoses and treatment plans, which are usually covered by insurance.

If you're in or around the Willamette Valley, request an appointment with one of our breast cancer doctors. We have cancer centers in Albany, Corvallis, Eugene, Lincoln City, Florence, Springfield, and Newport, Oregon, to help meet your needs close to home.