Hormone Therapy 101: What You Should Know

Hormone Therapy 101: What You Should Know

Reviewed by Jasper Clinical Board

Last updated 5/24/21

Hormones are your body’s chemical messengers. They play a huge role in regulating the most important functions, like eating, sleeping, exercising, and more. 
But sometimes, these hormones can “fuel” a cancerous tumor, telling it to grow or spread. If you have one of these “hormone-sensitive” cancers, doctors can fight it using a special kind of treatment called hormone therapy (also known as endocrine therapy). Here’s what you should know about this powerful treatment.

How does hormone therapy work?

Doctors use many different chemical and surgical tricks to make hormone therapy work, but they all boil down to two basic strategies: either block hormones from reaching the cancer, or prevent your body from making those hormones in the first place. Cutting off the fuel source in this way can make tumors shrink (or at least stop growing), making them easier to remove. It can also prevent cancer from returning in the years after treatment.
The most common kinds of hormone therapy use medication, which is either injected or swallowed. These treatments are considered “systemic,” because the medication moves through your whole body to find the target. This is different from local treatments (like radiation therapy) which only affect the area where your cancer is located. And it means that hormone therapy has some side effects you should know about (more on that shortly).
It’s less common, but there are also surgical options for hormone therapy. For instance, the ovaries or testicles can be removed to stop the body from producing the key hormones fueling a cancerous growth.

When is hormone therapy used?

Hormone therapy is typically used to treat one of four major cancer types: breast cancer, prostate cancer, endometrial (uterus) cancer, and adrenal cancer. It’s most often used in combination with other types of cancer treatment, such as surgery, radiation therapy (external, internal, or oral), or chemotherapy
Of course, whether or not your healthcare team recommends hormone therapy will depend on the specifics of your health, age, and unique medical circumstances. For instance, if you’re diagnosed with breast cancer, your doctor will typically take a small sample of the tumor (a “biopsy”) to test it. If your cancer is sensitive to estrogen or progesterone (about two-thirds are), then hormone therapy is an option.
There’s also a question of timing with hormone therapy. It can be used before other treatments to make a tumor smaller and easier to work with—i.e. “neoadjuvant hormonal therapy.” Or it can be used afterward, to lower the risk of your cancer returning—i.e. “adjuvant hormonal therapy.” In some cases, your healthcare team will advise using both adjuvant and neoadjuvant hormone therapy.

How long does treatment last?

Treatment time can vary enormously depending on your goals and how the cancer is responding. For instance, as a neoadjuvant treatment before breast cancer surgery, your healthcare team might recommend hormone therapy for just 2-4 weeks. During this time, you’ll have regular checkups that use imaging technology (such as a CT scan, MRI, or PET scan) to ensure the cancer is shrinking.
Similarly, if you’re treating prostate cancer, your healthcare team might recommend hormone therapy for 3 months before surgery. Again, during this time, you’ll have routine exams to measure the cancer’s progress. Your healthcare team will likely use a blood test called the Prostate-Specific Antigen (PSA) marker that shows how your cancer is responding to treatment.
As an adjuvant treatment, on the other hand, hormone therapy is often used for much longer durations. For instance, tamoxifen—a medication used to lower the risk of breast cancer recurrence - is commonly taken for 5-10 years after surgery / radiation therapy / chemotherapy.

Hormone therapy medications: The major classes

As we mentioned above, hormone therapy is powered by many different types of medication. Here are some big ones you might hear about:

Anti-estrogens / Estrogen blockers

As the name suggests, these medications target estrogen, which is often a key factor in the growth of breast cancer and endometrial cancer. They work by either blocking the estrogen receptors in your body’s cells or by suppressing your overall production of estrogen. This class includes selective estrogen receptor modulators (SERMs) like tamoxifen and raloxifene, and selective estrogen receptor degraders (SERD) like fulvestrant.

Aromatase inhibitors

Although they’re technically estrogen blockers, aromatase inhibitors (AIs) often end up in their own group. They work by blocking a process that converts other hormones into estrogen, thus lowering your estrogen count and starving the cancer.


This group of medications (which includes apalutamide, enzalutamide, and flutamide) blocks several hormones that feed prostate cancer - mainly testosterone and dihydrotestosterone (DHT).

Luteinizing hormone releasing hormone agonists (LHRH agonists)

This medication “shuts off” the ovaries, stopping their production of estrogen and helping starve breast cancer and endometrial cancer. Similarly, it stops the testicles’ production of testosterone, which is a key factor in the growth of prostate cancer.


As a synthetic version of your body’s natural progesterone, progestins can help slow the growth of endometrial cells. This makes them a powerful (and very common) tool in the treatment of endometrial cancer.

What about side effects?

As we said above, hormones are very important chemicals for your body to regulate itself. That means disrupting the natural flow of hormones can cause some unintended consequences for your hunger, sleep, sex drive, and more. Your healthcare team will prepare you for these issues in detail, but here’s what to expect:

Breast cancer hormone treatment side effects

  • Hot flashes
  • Nausea
  • Fatigue
  • Mood changes
  • Vaginal dryness
  • Low sex drive
  • Changes in menstruation

Endometrial cancer hormone treatment side effects

  • Hot flashes
  • Night sweats
  • Depression
  • Weight gain
  • Vaginal dryness
  • Muscle aches
  • Upset stomach
  • Blood clots or stroke (these are rare, but symptoms of these should be reported to your medical team immediately)

Prostate cancer treatment side effects

  • Hot flashes
  • Diarrhea
  • Nausea
  • Fatigue
  • Weakened bones
  • Enlarged, tender breasts
  • Low sex drive

Is hormone therapy right for me?

Hormone therapy is a powerful treatment that has helped countless people in their cancer experiences. But whether it’s right for you is a question only you and your doctor can answer. There are unique costs and benefits to hormone therapy, especially when combined with other medical efforts. As with every step of your treatment, it’s essential that you’re fully informed before making any decisions. So don’t hesitate to bring your questions and concerns to your healthcare team!

The content on this website is intended to provide the best possible information for you, but should not be considered—or used as a substitute for—medical advice. If you have questions about your diagnosis or treatment, please contact your health care provider(s). For questions or comments about this content, please email us at