Hormonal therapies for breast cancer: Weighing benefits and side effects

For people with hormone receptor-positive, HER2-negative breast cancer, blocking estrogen or preventing its formation is an essential way to reduce the risk of recurrence and improve survival. One major study looked at over 6,000 postmenopausal women who were prescribed tamoxifen, an aromatase inhibitor, or both for five years after surgery. They found that women who stopped taking their medication early were 35% to 56% more likely to have a recurrence; women who continued with treatment but did not consistently take it as prescribed were 61% more likely to experience a recurrence. Compared to no hormonal therapy, tamoxifen taken for five years after surgery provided a 40% to45% relative reduction in recurrence, and a 25% to30% relative reduction in breast cancer mortality, regardless of age, cancer stage, menopausal status, or chemotherapy use.

Despite these compelling numbers, studies show that up to a quarter of women never start their prescribed hormonal treatment; and over half do not take it as recommended. In a small study with men using tamoxifen for breast cancer, 20% discontinued treatment.

The reasons for stopping or skipping doses are clear: intolerable side effects, with scant hope to lessen them. Sure, chemotherapy, surgery, and radiation can be miserable, but these have an end in sight. The recommendation is for 5 years, 10 years, or sometimes even longer with selective estrogen receptor modulators (SERMs) such as tamoxifen; aromatase inhibitors (AIs) such as anastrozole, letrozole (Femara), and exemestane (Aromasin); and selective estrogen receptor downregulators (SERDs) such as fulvestrant (Faslodex).

As Peterson told her oncologist, “I didn’t beat cancer to be miserable. I beat cancer to live a life.”

Menopausal misery

The most common side effects of tamoxifen are the same ones that women often experience with menopause: vaginal dryness and painful intercourse, hot flashes, disrupted sleep, fatigue, mood swings, and (no surprise) loss of desire for sex. With aromatase inhibitors (AIs), muscle and joint pain also frequently occur. SERDs, which are currently approved for use in metastatic cancer, have the added discomfort of requiring a deep injection in each buttock monthly.

Where to start the conversation about hormonal therapy

Your decision-making should start with a conversation between you and your oncologist about risk, according to Virginia Kaklamani, MD, DSc, chair in breast cancer research and treatment and distinguished chair in oncology at MD Anderson Cancer Center, University of Texas Health, San Antonio. Specifically, what tumor biomarker (or genomic) testing shows about your individual cancer: its level of sensitivity to hormones and the likelihood that it will recur. Common tests used to determine this are the Oncotype DX, MammaPrint, and Prosigna. If you are premenopausal, the Breast Cancer Index also helps show if extending tamoxifen treatment from 5 years up to 10 years makes sense.

You should have the opportunity to evaluate your individual risk profile with your medical team and decide jointly what makes sense for you. Dr. Kaklamani explains: “If your results are estrogen receptor 2% positive and progesterone receptor negative — so you’re just a tiny bit positive — the impact of treatment is going to be pretty low. Then I would say ‘let’s try hormone therapy, but if you don’t tolerate it, I’m happy to stop because I know that it’s not going to benefit you that much.’” But she adds, “In most cases the estrogen receptors are 70% to 80% positive and progesterone receptors 80% to 90%, and then I know that hormonal treatment is the most important thing you need to understand.”

But far too often, these conversations just don’t happen. Cynthia Johnson was 39, premenopausal, and in a relationship when she found the lump that led to her diagnosis. She remembers that an Oncotype DX score was used to explain her need for chemotherapy. But she does not remember any conversation about how hormonal therapy could alter her risk of recurrence, or what side effects to expect from the oral Arimidex and Zolodex injections that were prescribed.

“At every appointment, they’d ask me how I felt, and whenever I complained, they said ‘those are just the side effects.’” She felt brushed aside, her concerns not heard or addressed.
She persisted, often talking to the team pharmacist, who became her champion. After months of her reporting bone and joint pain, exhaustion, low libido, and painful sex, they switched the Arimidex to exemestane (Aromasin), another AI. The side effects continued.

Johnson’s physician also prescribed duloxetine (Cymbalta), a type of antidepressant that can be helpful with bone and joint pain associated with AIs (it should not be taken with tamoxifen). However, she was not warned she shouldn’t stop Cymbalta suddenly. After missing one dose, she had a very bad reaction, leading her to drop Cymbalta altogether.

Social, economic, and professional burdens add up

As a self-identified plus-size woman, Johnson encountered a lot of skepticism that she was “just fat and lazy.” No one could see how much pain she was in every day. Plus, there was the $300 per month cost and the inconvenience of appointments for monthly injections.

“In my heart, I’m grateful for life, but I want some quality of life,” she says. When her AI medication mysteriously stopped coming from the mail order pharmacy, she took it as a sign and gave herself permission to stop hormone therapy. Today, as a Baddie Ambassador with For the Breast of Us, her affirmation is: “I will continue to make the best choices for me.”

Laura Peterson was 40 when her first mammogram revealed a mass that a biopsy showed to be a large, stage 0 breast cancer, ductal carcinoma in situ (DCIS). When lumpectomy was not able to remove the entire mass, she opted for mastectomy with an expander for reconstruction. However, her body rejected the expander and more surgery led ultimately to a DIEP flap reconstruction, with an involved recovery process that required a second surgery and transfusions. Altogether, in her words, it was “just a mess.”

With this treatment finally behind her, she started taking tamoxifen, which led to night sweats, dry eyes and skin, hot flashes, mood swings, and insomnia. On top of that, she needed to stop an antidepressant that had worked well for her, due to its incompatibility with tamoxifen. Her new antidepressant was not as effective.

“Your ability to manage side effects might be contingent on what kind of job you have and your flexibility to change hours,” says Peterson. “My job as a teacher is not very flexible. I need to be able to cope with a classroom of 12-year-olds. That year, it was terrible because they’re going through their own hormonal stuff. So, we were miserable together.”

Although it is rare, breast cancer does occur in men, and most cases are hormone-receptor-positive, requiring hormonal therapy. Only tamoxifen has been proven effective in men, who suffer some of the same side effects as women. In addition, many experience impotence.

Empower yourself through partnership

Dr. Kaklamani is adamant that it’s the physician’s job to ask the right questions and make sure you know your options for treatment and side effect management. “I don’t think we have any excuse to say, ‘Sorry, there’s just no other option.’”

There’s nothing wrong with seeking another opinion or even deciding that the chemistry is not right between you and a particular oncologist. “It’s extremely important for both physician and patient that their communication is satisfactory,” says Dr. Kaklamani. “Write down all your questions before you go to each appointment and make sure they are answered in a satisfactory way. If you ask repeatedly, and you still don’t get a good answer, then it might be time to find another provider.” Sometimes a nurse or nurse practitioner on your team will take more time to listen and be in a better position to support you.

Luckily, Laura Peterson found the understanding and partnership she needed from her oncologist. “I was in tears,” she remembers, “and, thankfully, he was very receptive when I asked ‘What are the odds if I stop tamoxifen?’” My cancer was 17% hormone receptor-positive, but I do have fibrocystic breasts and still have one lumpy breast with cysts and fibroadenomas. He reassured me that tamoxifen was an insurance policy for the left breast and they would monitor that carefully, every six months, to catch anything early.” Once she topped tamoxifen, the symptoms went away almost immediately.

Make it an ongoing dialogue

Virginia F. Borges, MD, MMSc, is the director of the Young Women’s Breast Cancer Translational Program at the University of Colorado Cancer Center and an LBBC Medical Advisory Board member. She sees many patients seeking second opinions about whether they need tamoxifen for 10 years. However, she notes that the data on its benefit for most women is 5 years of use, while 10 years may help people with higher-stage cancers.

“The idea of 10 years is pretty daunting when you're a 30-year-old who wants her sex life,” says Dr. Borges. “I always tell my patients that it's a process. We're going to talk about best choices and side effects to expect, and you're going to make a decision.” That discussion continues over time.

“Even if you've done three-and-a-half years of treatment, you've banked three-and-a-half years of benefit that nobody can take away from you,” says Dr. Borges, continuing, “There has to be willingness to have an open dialogue around the reality of the risk, and the reality of the benefit. If a woman is having horrible side effects, maybe 4% decrease in risk isn't it worth it. Conversely, I've got stage III patients where the benefit of these drugs is astronomically higher. Then we're going to work all the harder and push all the more to find a solution.”

In other words, every person must understand their own risk profile and then make the right decision for them.

Dr. Borges emphasizes this: “Your risk is your risk. You can’t increase your risk, we can only decrease it by using these treatments. You can choose to not decrease your risk, or you can choose to put up with the therapy for a certain length of time, and then you're going to say, ‘I got at least that much benefit and now I'm gonna roll my dice.’”

Manage hormonal therapy side effects

For hot flashes, studies have shown that acupuncture can be useful, as can lifestyle changes such as decreasing alcohol and caffeine, and drinking lots of water. If these aren’t effective, Dr. Kaklamani says that some people get relief from antidepressants or medications normally used for epilepsy, but these have their own side effects.

Managing hot flashes may help you sleep better, and good sleep hygiene is also very important. “When you can’t sleep, you’re really tired the next day and then all of these symptoms just get accentuated and your quality of life just gets worse,” says Dr. Kaklamani.

Ironically, the best solution for fatigue and joint pain is exercise. This can be a stroll with a friend or a pet, or 20 minutes walking on a treadmill, while enjoying your favorite movie or music.

When it comes to painful intercourse, Dr. Kaklamani observes that this is a serious quality of life issue for many people, especially when it affects their relationships. She points out that vaginal dryness and having a thin, estrogen-deprived vaginal wall cause most of the discomfort from penetration. While many women worry about using any estrogen-containing cream or suppository, ample research has confirmed that there is no increased risk for women using local estrogens while on hormone therapy. If just adding lubrication is insufficient, use of local estrogens is endorsed by the American College of Obstetricians and Gynecologists. Dr. Kaklamani further explains that these products help rebuild the vaginal wall in just a few weeks, and then no estrogen is absorbed into the rest of the body.

Dr. Kaklamani also suggests numbing the outside of the vagina with a mild lidocaine solution applied with a cotton ball before intercourse, combined with a good lubricant.

More tips

Get more proven strategies to manage hormonal therapy side effects here.

Find support

If you’re struggling with a decision about hormonal therapy, look in our Community section. Extended treatment can have a profound impact on your future health, so find out how others are managing. Ask how they get the attention they need from their care team or obtained second opinions. You are not the only one who has walked this path and you don’t have to go it alone.