What are the Side Effects of Hormone Therapy for Breast Cancer?

7 min read

What are the Side Effects of Hormone Therapy for Breast Cancer?

There are many different types of breast cancer, and treatment approaches will vary from person to person. Some types of breast cancer are known as hormone-positive, or HR+. For these patients, hormone therapy is often included in the overall treatment plan. Let’s look at hormone-positive breast cancer and the drugs used to help slow the growth of the cancer by blocking hormones, as well as the side effects that can occur.

What is Hormone Receptor-Positive Breast Cancer?

If you have hormone-positive breast cancer, the cancer cells in your body have receptors for estrogen, progesterone, or both. When you have higher levels of estrogen and/or progesterone in your body, cancer is given the fuel it needs to grow. Hormone therapy focuses on slowing the production of these hormones in order to slow down or stop cancer growth. 

Hormone therapy may be used after surgery to help reduce the risk of cancer recurrence. It may also be used before surgery to help shrink the tumor to make surgery easier. 

Types of Hormone Therapies for Breast Cancer Treatment

There are a couple of different drugs used for hormone therapy for breast cancer. Some common examples include Tamoxifen, aromatase inhibitors, and ovarian suppression. 


Tamoxifen acts as an estrogen antagonist, meaning it blocks the effects of estrogen to stop estrogen receptor-positive breast cancer cells from growing. Tamoxifen works by binding to the estrogen receptors on the cancer cells which blocks them from receiving the estrogen that causes the cancer to grow. It’s usually taken daily as a pill. When taken after cancer treatment to reduce the risk of recurrence, it is typically taken for five years, although there are some cases where it can be used up to 10 years. 

Tamoxifen is proven to reduce the risk of breast cancer coming back by 40% to 50% in post-menopausal women and by 30% to 50% in pre-menopausal women. It’s also shown to reduce the risk of a new cancer developing in the other breast by about 50%. 

Aromatase inhibitors 

Aromatase inhibitors block an enzyme called aromatase. Aromatase naturally works in the body to produce estrogen by turning the hormone androgen into estrogen. Aromatase inhibitors block this process from occuring so the amount of estrogen in the body is lowered. Some common types of aromatase inhibitors include: 

  • Arimidex (anastrozole)
  • Aromasin (exemestane)
  • Femara (letrozole). 

Aromatase inhibitors are usually prescribed to post-menopausal women. 

Ovarian suppression for premenopausal women

Ovarian suppression slows the growth of hormone receptor-positive breast cancer through either drug therapy or surgery. This treatment method works by preventing the ovaries from making estrogen, which stops menstrual periods and lowers hormone levels in the body. Ovarian suppression is done in combination with other hormone therapies (such as those listed above).

Drugs that are used for ovarian suppression include leuprolide (Lupron) and goserelin (Zoladex). Surgery is also sometimes used for ovarian suppression. This would involve the surgical removal of the ovaries. 

Breast Cancer Hormone Therapy


Side Effects of Hormone Therapy

There has been a great deal of discussion about the side effects of hormone therapies and quality of life. In fact, studies show that up to half of the patients using tamoxifen or another hormone therapy for breast cancer stop taking it because of the side effects that can occur. 

Common side effects of hormone therapy include:

  • Hot flashes
  • Night sweats
  • Changes in mood
  • Weight gain
  • Depression
  • Pain in the joints or muscles
  • Vaginal dryness or a vaginal discharge
  • Osteoporosis -- thinning of the bones 
  • Changes in memory and thinking
  • Increased risk of blood clots
  • Changes in the skin and hair

There are also other more severe side effects to be aware of such as:

  • Liver problems
  • Increased risk of stroke
  • Increased likelihood of cataracts developing in your eyes
  • Increased risk of endometrial cancer developing later

You should keep an open discussion with your cancer care team about how the hormone therapy makes you feel. 

How to Manage Side Effects of Breast Cancer Hormone Therapy

While the end result of the hormone therapy drug is proven to work well, dealing with the day-to-day discomfort of side effects can make it challenging. Some important steps you can take to help manage these side effects are listed below. 

Practice open communication with your healthcare team

By talking with your cancer care team about side effects, you can have an idea of what you might experience from a particular drug before starting the treatment. Write down any questions you have and bring them to your appointment to ensure that all of your concerns are addressed ahead of time. 

Managing hot flashes and night sweats

Side effects like hot flashes and night sweats can be uncomfortable and hard to get used to. Make sure to dress in loose-fitting clothing that is layered so you can easily shed a layer if needed. Try to avoid spicy foods, alcohol, and caffeine since these can make hot flashes worse. 

Take steps to manage weight

Some people gain weight as a side effect of hormone therapy. Take steps to manage your weight by exercising regularly and eating a healthy diet. Exercises like yoga and walking are some examples of gentle exercises that can help to keep you moving without being too strenuous. This is also helpful for reducing joint pain and stiffness.

Managing intimacy issues

Hormone therapy may cause you to have a lower sex drive or make sex uncomfortable due to vaginal dryness. Your doctor may be able to recommend some options to help manage these issues, such as vaginal lubricants or moisturizers and talking with a sex therapist or counselor. 

Supporting bone health through lifestyle choices

Some types of hormone therapy can cause thinning of the bones or osteoporosis. This can make your bones more fragile, placing you at a higher risk for a fracture or break. You can make certain lifestyle choices to help support your bone health to lessen this side effect. Some examples include quitting smoking and alcohol use, making sure you’re getting enough calcium and vitamin D, and exercising regularly. There may also be some drugs that can help with keeping your bones strong.

Taking steps to lower blood clot and cardiovascular risk

Hormone therapy can increase your odds of developing other health conditions, such as blood clots and heart conditions. To lower your risk of blood clots you can make sure to not sit in the same position for too long and wear compression socks throughout the day. To maintain your cardiovascular health, make sure you’re eating a nutritious diet and exercising regularly. Talk with your doctor about the additional steps you can take to prevent these side effects and what types of signs to look out for. 

Dealing with memory and thinking challenges

Hormone therapy can sometimes affect your ability to think and remember things. You may also hear of these side effects referred to as “cognitive changes.” You may have to take extra steps to manage these side effects by writing down reminders for yourself or having a friend or family member help you remember things. 

Weighing the Pros and Cons of Breast Cancer Hormone Therapy

These drugs are proven to significantly reduce the likelihood of breast cancer returning – in the same breast, the other breast, or in another area of the body. However, your quality of life during treatment is very important to you, and us. 

Side effects are a real possibility of hormone therapy, but it is important to keep in mind that most people don’t experience all of the side effects and some may develop over time. This makes it even more important to work closely with your healthcare team so they can tailor your dosage, length of total treatment, and other drugs that can help you manage some of the effects. 

You’ll also want to make sure to take steps to find emotional support through our community or professional counseling. This journey wasn’t meant to be taken alone; make sure to find supportive people you can lean on during this time. 

The team at Rocky Mountain Breast Specialists is here to provide you with a personalized breast cancer treatment plan. We’ll also listen to you and your concerns about various treatments. We work together with each patient to keep your quality of life as high as possible throughout hormone therapy as well as any other breast cancer treatments that are needed.

Request an appointment at one of our breast cancer centers throughout Colorado.

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