Side Effects of Hormonal Therapy for Breast Cancer
Hormonal therapy (also called anti-estrogen, endocrine, or hormone therapy) is used to treat all stages of hormone receptor-positive breast cancer. This breast cancer uses the hormones estrogen and progesterone to grow.
If you’ve been diagnosed with early-stage hormone receptor-positive disease, it’s likely your doctor will recommend you take hormonal therapy after surgery. Research shows taking one of these medicines for five to 10 years after mastectomy or lumpectomy lowers the risk of the breast cancer coming back (recurrence).
But there’s a catch: Some people find the side effects of hormonal therapy to be unbearable. Up to half of women who are prescribed hormonal therapy either don’t start the medicine, skip doses, or stop taking it early due to side effects, which include hot flashes/night sweats, weight gain, mood swings, vaginal dryness, and fatigue.
Hormonal therapy affects everyone differently. Your age, other health conditions, menopausal status can all affect how your body responds to hormonal therapy.
While some people have very severe side effects from hormonal therapy, other people aren’t bothered much. For most people, side effects begin within the first few months of the treatment.
Why does hormonal therapy cause side effects?
Most hormonal therapy medicines work by blocking estrogen from attaching to cancer cells or by reducing the amount of estrogen in the body. Without estrogen, hormone receptor-positive breast cancer cells can’t grow.
Healthy cells in your body — including in your brain, bones, uterus, vagina, and heart — also rely on estrogen. Hormonal therapy can interfere with how these cells function, leading to a variety of side effects.
Side effects of tamoxifen and other SERMs
Tamoxifen (brand name: Nolvadex) is one of the most well-known hormonal therapies. It's a type of medicine called a selective estrogen receptor modulator (SERM). Other SERMs include Evista (chemical name: raloxifene) and Fareston (chemical name: toremifene). Many people report that the most troublesome side effects of SERMs are hot flashes, night sweats, loss of libido, and vaginal dryness.
Common tamoxifen side effects include hot flashes, vaginal discharge or dryness, loss of libido, fatigue, and depression. Less common, but more serious side effects of tamoxifen include endometrial cancer, blood clots, and stroke.
Common Evista side effects include hot flashes, leg cramps, swelling, flu-like symptoms, and joint pain. Less common, but serious side effects of Evista include blood clots and stroke.
Common Fareston side effects include hot flashes, sweating, nausea, and vaginal discharge or dryness. Less common, but serious side effects of Fareston include a fast, slow, or irregular heartbeat and breathing problems.
Side effects of aromatase inhibitors
Arimidex (chemical name: anastrozole), Aromasin (chemical name: exemestane), and Femara (chemical name: letrozole) are aromatase inhibitors (AIs). Bone and joint pain are considered the most problematic aromatase inhibitor side effects.
Arimidex, Aromasin, and Femara have similar side effects, including joint and bone pain, hot flashes, vaginal dryness, and high blood pressure. More serious side effects include heart problems and bone loss.
Side effects of Faslodex and other SERDs
Faslodex (chemical name: fulvestrant), imlunestrant (brand name: Inluriyo), and Orserdu (chemical name: elacestrant) are medicines called selective estrogen receptor downregulators (SERDs). These medicines are only prescribed for advanced-stage or metastatic breast cancer.
A number of people say that the pain from Faslodex injections is the most troubling side effect. Because imlunestrant and Orserdu are relatively new, there isn’t as much feedback on side effects. Some people report nausea being a problem, though they are able to manage it with medicine.
Common Faslodex side effects include injection site pain, nausea, bone and muscle pain, hot flashes, and headache. In rare cases, Faslodex can also cause bleeding problems.
Common imlunestrant and Orserdu side effects include nausea, fatigue, vomiting, joint pain, and loss of appetite. Less common, but severe side effects include heart attack and stroke.
Conditions that can make side effects worse
If you have other health conditions, you may have more severe side effects from hormonal therapy. For example, if you have arthritis, your joint pain may become worse. If you’ve already been experiencing menopausal symptoms, they might become more severe when you start hormonal therapy.
Pre-menopausal women who are prescribed hormonal therapy face distinct challenges, including having to deal with menopausal symptoms like vaginal dryness and hot flashes at a much younger age than they normally would. Hormonal therapy can also affect fertility and plans to have children because you can’t take these medicines while pregnant or trying to get pregnant. (That said, research suggests that pausing hormonal therapy to get pregnant is safe and does not affect your risk of recurrence. Longer follow-up studies are needed to confirm these findings.)
Men taking hormonal therapy for breast cancer may have side effects that take them by surprise, including hot flashes, erectile dysfunction, loss of libido, weight gain, mood swings, and gynecomastia (breast growth or swelling).
Managing side effects of hormonal therapy
The side effects of hormonal therapy can be painful and frustrating, but these medicines reduce the risk of hormone receptor-positive breast cancer coming back.
This doesn’t mean you need to suffer in silence, though. Use a symptom tracker or jot down any symptoms you have once you start taking the medicine, including the days and time of day you experience them, as well as how long they last.
Don’t wait for symptoms to become severe — talk to your healthcare team about these symptoms as you notice them.
Hot flashes
There are a number of ways to ease hot flashes.
Avoid hot flash triggers such as stress, cigarettes, alcohol, caffeine, diet pills, spicy food, hot food or drink, hot tubs, saunas, hot showers, hot rooms, and hot weather.
Reduce the fat in your diet. Over time, a low-fat diet helps some people with hot flashes.
Dress in loose and airy fabrics such as cotton, linen, and rayon.
Keep ice water nearby so you can sip it to cool down. Pack a small cooler full of cold water to carry with you.
Take a cool shower before going to bed.
Consider natural remedies. Techniques that may help include meditation, massage, yoga, and acupuncture.
Ask your doctor about medications. There are several prescription medications for hot flashes.
Bone and joint pain
Many people use a combination of techniques to manage joint and bone pain.
Try over-the-counter pain medications. Naproxen and ibuprofen may help you manage bone and joint pain.
Consider complementary and holistic therapies. Acupuncture, chiropractic therapy, massage, music therapy, and hypnosis have been shown to reduce pain.
Use hot or cold packs, or a combination of the two, to soothe sore areas. Heat can help reduce muscle spasms and cold can help reduce inflammation.
Eat a healthy diet that includes enough calcium and vitamin D to keep your bones as strong as they can be.
Maintain a healthy weight to ease stress and strain on your joints.
Exercise regularly. Exercise keeps your bones strong and helps your joints stay flexible.
Fatigue
Managing cancer fatigue usually involves several techniques and may include treating other side effects, such as pain and insomnia.
Eat a healthy diet that includes lots of fresh, unprocessed food, including fruits, vegetables, and lean protein.
Exercise regularly. Exercise can ease fatigue and helps improve your stamina.
Try a nap in the daytime, but try to keep it short and not sleep past 2 p.m., so you’re able to sleep at night.
Keep to a sleep routine. Go to bed at the same time each night and get up at the same time each morning. Don't stay in bed after you wake up. Make sure you get enough sleep and that you sleep for the same amount of time each night.
Organize each day. Figure out what you have to do and when you need to do it. Pacing yourself helps to conserve your energy. Give yourself more time for activities that take concentration.
Make lists and ask for help. Get help with little things: taking out the trash, folding the laundry, or paying bills. Keep a list of things you need done so when people ask what they can do, you can give them the list.
Before you give up on hormonal therapy…
If you’ve been diagnosed with early-stage breast cancer, you may get to a point where you feel that the side effects are too much and you want to stop taking tamoxifen or an aromatase inhibitor. If you find yourself there, talk to your doctor about your options. You may be able to reduce the dose of the medicine you’re taking or they may have other ideas about ways to reduce troublesome side effects. You may also be able to switch to a different hormonal therapy medicine.
If you do decide to stop taking hormonal therapy, the side effects usually resolve in a few days to a few weeks.
Sharing your feelings with others who are in the same boat can also help. Your nurse or doctor can put you in touch with a support group in your area. There are also online support groups and discussion forums. Discussing your feelings with a therapist can also help you process what you’re going through.
