All cancer treatments come with side effects. Knowing what to expect as you start treatment can help you prepare for what’s ahead. These are the treatments doctors typically offer for HR+/HER2- breast cancer with mutations, their side effects, and ways to manage them.
Endocrine (Hormone) Therapy Side Effects
Endocrine therapy is the go-to treatment for most HR+/HER2- breast cancers, even if they involve mutations. Sometimes you’ll have endocrine therapy in combination with a targeted treatment for your cancer’s genetic mutation.
Aromatase inhibitors
Aromatase inhibitors work by reducing the amount of estrogen in your body. This is what causes many of the side effects of the drug. Estrogen supports your sexual and reproductive health and helps keep your bones and heart healthy. Lowering the amount of estrogen in your body can affect your overall health.
The most common side effects of aromatase inhibitors include:
- Muscle pain (myalgia)
- Joint pain and stiffness
- Hot flashes
- Vaginal dryness
- Cardiovascular disease
Taking aromatase inhibitors also raises your risk of osteoporosis (a disease that makes bones weak and brittle) and bone fractures.
To counteract these effects, you can:
- Take medication for joint pain and stiffness. Over-the-counter nonsteroidal antiinflammatory drugs (NSAIDs) such as ibuprofen reduce swelling and pain. Or your doctor may prescribe a medication called duloxetine (Cymbalta). This drug treats fibromyalgia pain and may help treat the arthritis-like pain and swelling in your joints.
- Adopt a regular exercise plan. Consistent physical activity, especially weight-bearing exercises like walking, tennis, or dancing; resistance exercises with weights; or balance exercises like yoga help keep bones healthy and increase bone strength.
- Monitor and boost bone density. Your doctor can monitor your bone health with bone scans to help ward off bone thinning before it happens. You may also take resorption medications such as bisphosphonates or denosumab (Prolia, Xgeva) to strengthen your bones.
- Help temper hot flashes. You may be a good match for medications that can help hot flashes, such as selective serotonin reuptake inhibitors (SSRIs) like paroxetine (Brisdelle) or a medication that blocks chemicals in the brain related to hot flashes called fezolinetant (Veozah). But you can also make some lifestyle changes to help hot flashes. Wear loose, breathable clothing in layers you can remove when you need to, avoid heat triggers such as spicy foods, stay hydrated, and practice relaxation techniques such as meditation and deep breathing.
- Try vaginal lubricants. To ease dryness, over-the-counter lubricants can add moisture to your vagina during sex. Other products called vaginal moisturizers can help with moisture at other times of the day.
- Connect with a cardiologist. Because treatment with hormone therapy raises your risk of heart attack and stroke, your doctor may refer you to a cardiologist to keep tabs on your heart. A healthy lifestyle is key, including eating a heart-healthy diet, getting regular exercise, and reducing stressors in your life.
Tamoxifen
Tamoxifen works by blocking estrogen’s access to your cells. Some of the side effects are similar to aromatase inhibitors. The most common include:
- Menopause-like symptoms, including hot flashes, night sweats, and vaginal dryness
- Weight gain
- Fluid retention (edema)
- Irregular or no periods
- Leg swelling
- Nausea
- Vaginal discharge
- Skin rash
- Fatigue
- Headaches
Some more serious side effects can include:
- Blood clots, deep vein thrombosis (DVT) and strokes
- Cataracts or other eye problems
- Endometrial (uterine) cancer
Try these tips for managing tamoxifen side effects:
- Take with food. This can help settle your stomach and reduce nausea.
- Ask for nausea meds. Your doctor may be able to prescribe a medication to take away your sick feeling.
- Move your body. It seems counterintuitive, but getting some form of exercise can help boost your energy when you feel fatigued. Movement also helps encourage circulation and reduce swelling.
- Use fragrance-free, gentle cleansers. Since tamoxifen can cause a rash, take extra care with your skin. Your doctor may also be able to suggest creams to soothe your rash.
Fulvestrant (Faslodex)
This drug binds so tightly to estrogen receptors that they break down, and estrogen can’t have the same effect on your cancer. In addition to the effects you may see with other hormone therapies, you may also have:
- Soreness or swelling where the needle went in your skin
- Liver changes (these typically go back to normal after treatment stops)
- Allergic reaction (tell your doctor right away if you notice trouble breathing, hives, or other allergic symptoms)
- Headache
- Loss of appetite
- Urinary tract infection
- Numbness or tingling in the toes
To manage these side effects, try:
- Apply cold. You can hold cold compresses to your injection area to reduce swelling and pain.
- Antibiotics. These can treat infections in your urinary tract.
- Prioritize rest. Headaches and fatigue can get worse if you’re not getting the sleep or downtime you need.
- Try physical therapy. These specialists may help with numbness or tingling you’re feeling in your feet by prescribing braces or other devices.
Targeted Treatment Side Effects
One benefit of targeted treatments is they focus on a very small piece of your cancer puzzle in an effort to manage the disease. Targeted treatment sometimes has less side effects than other treatments like chemotherapy since the medication specifically targets cancer cells.
Kinase inhibitors
These include work by blocking certain proteins and help keep cancer cells from growing.
Common side effects of kinase inhibitors in general, which include drugs like imatinib (Gleevec) and lapatinib (Tykerb), include:
- Nausea
- Vomiting
- Diarrhea
- Fatigue
Side effects specific to CDK4/6 inhibitors such as abemaciclib (Verzenio), palbociclib (Ibrance), and ribociclib (Kisqali) include:
- Hair loss (alopecia)
- Infections
Side effects specific to PIK3CA inhibitors like apelisib (Piqray) and inavolisib (Itovebi) include:
- High blood sugar (hyperglycemia)
- Rash
- Swollen mouth or lips (stomatitis)
mTOR inhibitors
If you’re taking an mTOR inhibitor like everolimus (Afinitor) as a targeted therapy, in combination with hormone therapy, it may cause side effects such as:
- Infection
- Anemia
- Bruising and bleeding
- Sore mouth and throat
- Diarrhea
- Lung problems
- Changes to taste
- High blood sugar
AKT inhibitors
If you have an AKT1 gene mutation and are taking capivasertib (Truqap) as treatment, you may have these side effects:
- Diarrhea
- High blood sugar levels
- Low blood cell counts, including white blood cells and platelets
- Nausea
- Skin reactions
These tips can help you manage targeted therapy side effects:
- Call your doctor at the first signs of infection. These include fever, chills, shakiness, needing to pee more often, or diarrhea. Your doctor can test you for infection and treat it before it becomes serious.
- Boost red blood cells and platelets. Anemia (low red blood cell count) makes you weak, tired, cold, and breathless. Your doctor will be keeping tabs on your blood cell counts and can suggest treatment such as an iron infusion or even blood transfusion if you need it. A platelet infusion may help with bruising and bleeding. You can also eat high-iron foods such as red meat, dark, leafy greens, and beans.
- Care for your mouth. Avoid mouthwashes with alcohol if you have a sore throat or mouth. Ask your doctor about medicated rinses or gels that can relieve pain.
- Don’t smoke. Cigarette smoke and nicotine make many side effects worse, as well as harming your overall health. Talk to your doctor if you need help finding a smoking cessation plan.
- Ward off diarrhea. Over-the-counter diarrhea medications can help. Make sure you’re drinking plenty of fluids each day to counteract any diarrhea you’re having.
- Get a lung check. If you’re noticing wheezing, coughing, or trouble breathing, tell your doctor. You may need inhaled steroids to help you breathe better.
- Snack small and often. If your appetite is an issue, go for nutrient-dense small bites frequently during the day instead of waiting to have three larger meals.
Taking Care of Yourself While Treating Your Disease
No matter which treatment or treatments you take for your HR+/HER2- breast cancer with mutations, you’ll benefit from the support of family and friends. Don’t be afraid to ask for help with things that are more difficult now that you’re managing cancer care.
As you notice what’s harder to do, make a list of concrete jobs others can take off your plate. Those might include mowing your grass, vacuuming your house, or picking up your grocery order from the store.
You may find connection with a support group to be a valuable resource.
Show Sources
Photo Credit: E+/Getty Images
SOURCES:
Cleveland Clinic: “Aromatase Inhibitors,” “Tamoxifen.”
American Cancer Society: “Hormone Therapy for Breast Cancer,” “Hot Flashes and Sweating,” “Targeted Drug Therapy for Breast Cancer,” “Anemia in People With Cancer,” “Mouth Soreness and Pain.”
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS): “Exercise for Your Bone Health.”
Johns Hopkins Health: “Vaginal Dryness During Breast Cancer Treatment.”
American Heart Association: “Some cancer survivors could have increased risk for heart problems after hormone therapy.”
Cancer Research UK: “Tamoxifen,” “Nerve changes and cancer drugs.”
MacMillan Cancer Support: “Tamoxifen,” “Everolimus.”
MD Anderson: “Migraine headaches in cancer patients: How to prevent and treat them.”
Therapeutic Advances in Medical Oncology: “CDK4/6 inhibitors: basics, pros, and major cons in breast cancer treatment with specific regard to cardiotoxicity – a narrative review.”
