Understanding Hormone Therapy Amid Breast Cancer Treatment
- Actress and mom of two Olivia Munn, 46, has described herself as being in “the long haul” of hormone-suppression therapy to reduce her risk of breast cancer recurrence and started a new “series” on Instagram to further talk about her journey.
- Munn’s type of breast cancer, called hormone receptor-positive (HR+), means that the hormones estrogen or progesterone stimulate cancer cell growth, which is why HR+ cancer is typically treated with hormone therapy drugs that lower estrogen levels or block estrogen. Her sub-type, luminal B, meant that her cancer was specifically estrogen-fueled.
- After a double mastectomy, hysterectomy and removal of her fallopian tubes and ovaries, Munn began hormone-suppression therapy.
- Menopause is when a woman has gone 12 consecutive months without a menstrual period, but it is vastly more complex than its simple definition. The average age at which a woman starts menopause is around 51. However, certain medical treatments — such as chemotherapy, radiation, surgical removal of the ovaries, or hormone-suppressing drugs used in some cancer treatments — can also induce menopause.
- If you or someone you love is navigating menopause or cancer, you don’t have to face every question alone. SurvivorNet’s My Health Questions, an AI-powered tool, can help you find answers to everyday cancer questions, better understand treatment options, and feel more informed along the way.
In an effort to give back to others in the same way she has been supported since her April 2023 diagnosis, Munn has taken to Instagram to start what she’s calling a new “series” to further strengthen the sisterhood of women battling breast cancer.
Read MoreFollowing Munn’s battle with hormone receptor-positive (HR+) breast cancer, she has spent about two years on anastrozole (Arimidex), a hormone therapy that lowers estrogen levels in the body to reduce the risk of the cancer returning—something she previously described as “exhausting.”
View this post on Instagram
Munn, who beat cancer after undergoing a double mastectomy [surgical removal of both breasts], hysterectomy, and removal of her fallopian tubes and ovaries, explained in the footage, “This is healing for me too, because I know that just simply talking about my breast cancer journey is going to be helpful for someone out there because every time I felt lost in the beginning of my journey, I would look online and I would see another woman talking about it. And it just, it gave me just a little bit more hope that things would be okay.”
She then proceed to answer the her most-asked question of, “How am I doing today?”
Munn explained, “Today, I’m doing really good. Now, I think most people who are going through any type of cancer can tell you that every day is different. And sometimes you feel like you’re really on an upswing, and then there are other times when you’re like, oh my gosh, this is so difficult. How is this still so hard? And what does my life look like on a daily basis right now?
“Well, I’ve got my two kids, four and a half and 22 months old, and they’re just the best things in the whole world. I’m filming, I’m working, traveling with my husband as he’s working.”
She continued, “When it comes to the medical side, I went into a surgical menopause, which I will talk about in another video. And that means I went from not being menopausal or perimenopausal to just instant menopause. And not only that, but I’m on another medication called an aromatase inhibitor that shuts down testosterone production that turns into estrogen in my body.
“Those medications are very difficult. It’s the stuff we have to do after the big hurdles that are kind of like, there’s big hurdles and there’s like long hurdles. And I’m in the long hurdle right now. I can’t wait to do the second one now that I’ve taken a lot of pressure off of myself.”
Hormone Therapy: A Key Defense Against the Most Common Type of Breast Cancer
For many women diagnosed with breast cancer, the disease is fueled by hormones—specifically estrogen or progesterone. These are known as hormone receptor-positive cancers, and they represent the most common subtype of breast cancer.
“For women who have hormone-positive breast cancer, it means that they have a cancer that needs estrogen to grow,” Dr. Elizabeth Comen, medical oncologist at Memorial Sloan Kettering Cancer Center, explained to SurvivorNet.
RELATED: Hormone Therapies for Breast Cancer: Aromatase Inhibitor
Hormone therapy is designed to block or lower the hormones that help cancer cells grow. It’s a cornerstone of treatment for hormone receptor-positive breast cancer, and it plays a vital role in both treatment and prevention.
“Endocrine therapy has significant benefits in reducing the risk of breast cancer recurrence and improving breast cancer survival,” says Dr. Eleonora Teplinsky, head of Breast Medical Oncology at Valley Health System.
These therapies work in two main ways:
- Lowering estrogen levels in the body
- Blocking estrogen receptors on cancer cells so the hormone can’t fuel tumor growth
One widely used drug is Tamoxifen, which blocks estrogen’s ability to bind to cancer cells. It’s used not only to treat breast cancer but also to help prevent it in women with a strong family history or other risk factors.
Another class of drugs, called aromatase inhibitors, works by stopping the body from producing estrogen altogether. These are typically prescribed to postmenopausal women and include:
- Anastrozole (Arimidex)
- Letrozole (Femara)
- Exemestane (Aromasin)
All are taken as daily pills and have been shown to slow or stop the growth of estrogen-sensitive tumors.
Munn’s Hormone Therapy Journey
Munn began hormone suppression therapy back in the latter part of 2023. She told People in an earlier interview, after beginning treatment, she started to experience medically induced menopause.
She first took Lupron (generic name leuprolide), a hormone therapy shot that aims to reduce her estrogen levels to prevent cancer from growing, but the drug made Munn feel “next-level, debilitating exhaustion,” she told People.
The side effects prompted Munn to ask for a different medication.
Munn has since been on a five-year hormone suppression plan and taking the drug Anastrozole (brand name: Arimidex) since August 2024.
Expert Resources On Hormone Therapies
- When My Cancer Becomes Resistant To Hormone Therapy: What Are Your Options?
- Can Hormone Replacement Therapy Increase Your Risk of Cancer? Understanding the Connection
- Hormone Therapies for Breast Cancer: Aromatase Inhibitor
- Hormone Therapies for Breast Cancer: mTOR Inhibitors
- Hormone Therapies for Breast Cancer: CDK 4/6 Inhibitors
It’s helpful to understand that in postmenopausal women, there is still some production of the hormone estrogen even though the ovaries have largely shut down. Drugs called aromatase inhibitors are used to block the activity of the aromatase enzyme and, therefore, stop the production of estrogen. This helps slow down the growth of tumor cells that are sensitive to estrogen.
In most premenopausal women, the ovaries produce too much aromatase for these inhibitors to work effectively. However there is some evidence of benefit of these drugs in premenopausal women if their risk of recurrence is high enough that they’re also getting chemotherapy, but the evidence is not strong, so this should be discussed with one’s doctor.
Examples of aromatase inhibitors include anastrozole (Arimidex), letrozole (Femara), and exemestane (Aromasin). All of these are in the form of pills that are taken once a day.
In an earlier Instagram post, Munn revealed the following timeline of her breast cancer journey:
- January 2022 — 2 Mammograms, 2 Ultrasounds: Clear
- January 2023 — Mammogram: Clear
- February 2023 — Genetic Testing: 0% Chance of Genetic Cancer
- March 2023 — Tyrer-Cuzik Breast Cancer Assessment Score: 37.3%
- March/April 2023 — MRI+ Ultrasound + Biopsies
- April 2023 — Bilateral Breast Cancer Diagnosis
- May 2023 — Nipple delay, Lymph Node Dissection and Double Mastectomy
- June 2023 — Egg Retrieval
- September 2023 — Breast Reconstruction
- November 2023 — Begin Lupron
- April 2024 — Partial Hysterectomy/ Oophorectomy
- August 2024 — Begin Arimidex
Understanding Hormone Therapy For Breast Cancer
Hormone therapy for breast cancer is one line of defense in the vast tool kit for treatment.
It’s used for hormone receptor-positive cancers, which are actually the most common types of breast cancers. When a tumor is “hormone receptor-positive,” it means that a pathologist has run special tests on the cancer to determine that it is positive for either the estrogen and/or progesterone receptor.
WATCH: Understanding hormone therapy for breast cancer.
When a certain type of cancer tests positive for being hormone-receptive, it means that the cancer needs the hormones estrogen and/or progesterone to grow.
Your doctor will then determine what type of treatment is best for your type of cancer.
It’s important to note that approximately half of early-stage hormone receptor-positive breast cancers stop responding to hormone therapy.
These cancers can be compared to a room with a light switch. Initially, the breast cancer has just one light switch that you need to hit to turn off the lights. But as the breast cancer mutates, it grows an additional light switch, so now you must hit both at the same time if you want to kill the cell.
Hormone Therapies for Breast Cancer: mTOR Inhibitors
Almost all advanced-stage, hormone receptor-positive cancers eventually become resistant to hormone therapy. But by combining hormone therapy with a new class of drugs called mTOR inhibitors, doctors can hit both switches at once. The mTOR inhibitors act on proteins called kinases, slowing down the cancer’s growth
Understanding Menopause & How It Affects The Body
Menopause is when a woman has gone 12 consecutive months without a menstrual period, but it is vastly more complex than its simple definition. The average age at which a woman starts menopause is around 51. However, certain medical treatments — such as chemotherapy, radiation, surgical removal of the ovaries, or hormone-suppressing drugs used in some cancer treatments — can also induce menopause.
According to leading experts in menopausal care, menopause is a major life and health transition that can affect much more than reproductive health. Symptoms extend far beyond hot flashes and can affect nearly every aspect of a woman’s physical, emotional, and cognitive life. It can influence sleep, mood, cognition, sexual health, heart health, bone health, and overall well-being.
Dr. Sarah Richina, Director of UPMC Magee-Womens Midlife Health Center in Pittsburgh, who advocates for personalized, interdisciplinary care to improve women’s long-term health and well-being, recently spoke with SN Health on how menopause can leave women feeling like they’re struggling to keep up.
“What we see and hear a lot is patients coming in and saying, ‘I don’t feel like myself,’” Dr. Richina told SN Health, noting that menopausal changes can bring a “period of vulnerability.”
“It also comes at a time when there are a lot of responsibilities. You might be caretaking for your parents who are aging, or your children are growing and leaving home. And so, there are a lot of transitions happening in people’s lives at this point.”
SN & You: Discussing Sex and Sexuality After Cancer
SurvivorNet also spoke with Dr. Yuan Yuan, breast medical oncologist and medical director for breast cancer research at Cedars-Sinai Medical Center, and asked how they tackle the topic of sexual health with breast cancer patients.
“I think it’s important,” she says on the overall subject, but explains that during the visit with a provider, you only have so much time. “You’re focused on chemo side effects, labs, imaging, you know, a lot of things … it’s taken up all the time,” Dr. Yuan Yuan explained. “So sex has become being pushed to the corner.”
RELATED: Hormones & Mood Swings: Why Anxiety & Emotional Changes Intensify In Perimenopause
Dr. Stephanie McNally, Medical Director for Katz Institute of Health at Northwell Health, also spoke with SN Health and validated the emotional symptoms many women experience as they enter menopause, adding that they aren’t imagined or exaggerated.
“There’s very good data to show that there is an increase in depression and anxiety diagnoses in the perimenopausal transition,” Dr. McNally said.
The reasons are both biological and situational:
- Shifts in estrogen and progesterone
- Life stressors are common in midlife, which may include caring for aging parents, career pressures, caregiving, or relationship changes.
- Elevated stress hormones like epinephrine and cortisol
These forces interact in ways that can destabilize mood, energy, and sleep.
Dr. McNally described these symptoms as a tightly linked system:
“If you break it down into a physiological hormonal perspective… these stress hormones could negatively impact many other factors of your life,” Dr. McNally explains.
“If you’re not sleeping as a root, your other mood function fatigue is all connected. Think of it as a triangle. Sleep, mood, and energy are very, very connected.”
Support Through Health Challenges
Having a strong community around you, as Munn does, between her husband, her children, friends and loved ones, is ideal when challenged by health struggles.
Dealing with cancer or any sort of health battle for that matter can be overwhelming, so having physical and emotional support is crucial. That being said, it’s very important to know your limits on what you can handle as you undergo treatment and recover from your cancer, and that includes relationships.
“Going through [cancer] treatment is a very vulnerable and emotionally exhausting experience,” licensed clinical psychologist Dr. Marianna Strongin wrote in a column for SurvivorNet.
“Noticing what you have strength for and what is feeling like too much, [is] extremely important to pay attention to as you navigate treatment.”
Dr. Strongin does note, however, that having people by your side during this “arduous chapter” of your life can be hugely beneficial.
“Studies have found consistently that loneliness is a significant risk factor for physical and mental illnesses and the trajectory of recovery,” she wrote. “Therefore, it will be important that you surround yourself with individuals who care and support you throughout your treatment.”
Contributing: SurvivorNet Staff
Learn more about SurvivorNet's rigorous medical review process.
