Managing Side Effects of Treatment for Metastatic Breast Cancer: You're Not Alone

This article is for people who have hormone receptor (HR)-positive HER2-negative metastatic breast cancer (MBC), or their care partners, as well as others who want to learn more about HR-positive HER2-negative MBC. The goal is to better understand possible side effects of treatment and how the patient, their care partners, and care team can work together to manage them.

You will learn:

• Treatments for HR-positive HER2-negative MBC

• Side effects you may experience from these treatments

• When to contact your doctor about side effects

• Tests your doctor may recommend to monitor side effects

• When side effects may require a change in what treatment your doctor recommends

• Helpful resources for managing side effects

Treatment options for your MBC depend on where the cancer has spread, your overall health, the levels of estrogen or progesterone hormone receptors (HRs), and the HER2 gene in your tumor.

Cancers are called HR-positive if they have estrogen or progesterone receptors.

Cancers are called HER2-negative if they do not have high levels of the HER2 gene.

There is no one treatment for HR-positive HER2-negative MBC. Treatment is based on menopause status, whether you have a mutation (change) in the BRCA gene, past breast cancer treatment, how quickly your breast cancer grows, other health problems you have, other needs you may have, and your preferences.

Types of treatment include chemotherapy, radiation therapy, hormone (or endocrine) treatment, and targeted treatment.

Chemotherapy may or may not be given first. It is often the first treatment if the cancer is large, causing symptoms, growing quickly, or affecting the organs. It can also be used if other treatments have stopped working.

HR-positive breast cancers can be treated with hormone therapy medicines that lower estrogen levels or block estrogen receptors.

Hormone therapy is the primary treatment for HR-positive MBC because it slows the growth and spread of the tumor.

Medicines include:

• Selective estrogen receptor modulators (SERMs)

• Aromatase inhibitors (AIs)

• A selective estrogen receptor downregulator (SERD)

Targeted medicines block the growth and spread of cancer cells. Sometimes these medicines work when chemotherapy does not, and sometimes they help other types of treatments work better.

Types of targeted medicines include:

• CDK4/6 inhibitors

• mTOR inhibitors

• PARP inhibitors

All treatments and medicines can have side effects. Some are mild or bothersome, while others can be severe or serious. The ones you might have will depend on the types of treatment you are on and how your body responds to the treatment.

Before you begin treatment, talk with your doctor about what side effects you may have; which ones need immediate medical attention; and when you should contact your doctor, call 911, or go to the emergency room.

Ask your doctor, nurse, or pharmacist to review the Medication Guide for patients included with all prescription medicines. This guide tells you how to take your medicine, side effects you could have, and what to do if you have serious side effects.

Some common side effects of chemotherapy you can recognize are:

• Hair loss or thinning (alopecia)

• Nausea, vomiting, and constipation or diarrhea

• Symptoms of menopause, such as loss of periods, hot flashes, mood swings, night sweats, and vaginal dryness

• Tiredness or weakness (fatigue)

Other possible side effects your doctor can check or test you for include:

• Mouth and throat sores

• Low red or white blood cell counts

• Heart problems

• Blood or bone marrow cancer

Treatment with radiation therapy may include these common side effects you can recognize:

• Skin irritation and redness

• Breast changes or swelling

• Tiredness or weakness (fatigue)

• Swelling in one or more of the arms or legs

• Dry cough or trouble swallowing

Common side effects of hormone therapy you can recognize are:

• Symptoms of menopause, such as hot flashes, mood swings, night sweats, and vaginal changes

• Joint and muscle pain

• Tiredness or weakness (fatigue)

• Nausea

Other side effects your doctor may test or check for include:

• Cataracts (clouding of the lens in the eye)

• Endometrial or uterine cancer

• Liver or heart problems, including stroke or blood clots

• Osteoporosis (bone loss)

CDK4/6 inhibitors may cause these common side effects that you can recognize:

• Nausea, vomiting, and constipation or diarrhea

• Tiredness or weakness (fatigue)

• Hair loss or thinning (alopecia)

Other side effects that your doctor can check or test you for may include:

• Mouth and throat sores

• Low red or white blood cell counts

• Blood clots in veins or lungs

• Heart or liver problems

If you’re taking an mTOR inhibitor, side effects you can recognize include:

• Nausea, vomiting, or diarrhea

• Swelling in the hands, arms, feet, ankles, or legs

• Tiredness or weakness (fatigue)

Other side effects that your doctor can check or test you for include:

• Kidney or lung and breathing problems

• Mouth and throat sores

These side effects that you can recognize may occur if you are taking a PARP inhibitor:

• Nausea, vomiting, and constipation or diarrhea

• Tiredness or weakness (fatigue)

• Changes in the way food tastes, loss of appetite, and indigestion or heartburn

• Hair loss or thinning (alopecia)

Other side effects that your doctor can check or test for are:

• Mouth sores

• Low red or white blood cell counts

• Bone marrow or lung problems

• Changes in how your kidneys work

Some side effects need to be reported to your doctor right away. Ask your doctor what side effects require you to call 911 or go to the emergency room.

Call your doctor immediately if you have:

• Bloody stool; nausea, vomiting, constipation, or diarrhea that’s severe or longer than 2 to 3 days

• Chest pain

• Cough that’s new or won’t go away

• Dry, burning, scratchy, or "swollen" throat

• Mouth sores, swollen tongue, bleeding gums

• Need to urinate urgently or more often, burning, blood in your urine

• Temperature over 100.4°F (fever) or chills

• Trouble breathing, shortness of breath

Your doctor will do tests every few months to see how well treatment is working and to check on symptoms and side effects.

Types of tests you may have are:

• Blood tests for blood cell counts, liver function, and proteins that show if treatment is working (tumor markers)

• X-rays, like a chest x-ray

• CT scan or PET scan

• Bone scan or bone density test to check for osteoporosis (bone loss)

Tell your doctor about any side effects you have. Together, you can discuss ways to manage them. It may be helpful to keep a list of your symptoms to take to doctor’s visits.

Common side effects can include nausea, diarrhea, fatigue, and hair loss (alopecia), depending on which medicine(s) you’re taking.

Your doctor may prescribe medicines to help with these and other side effects --the ones you can see or feel (symptoms) -- and the ones you can't feel, like low blood cell counts. This is why testing for side effects is important -- to find out if you’re having side effects that you don't see or feel.

Prescription medicines may help with side effects such as diarrhea, nausea, vomiting, skin irritation, loss of appetite, and low red or white blood cell counts. In some cases, your doctor may prescribe medicine ahead of time to help prevent side effects.

Many side effects can be reversed if treatment is changed or stopped. Once treatment ends, most side effects go away.

You can also ask your doctor for a recommendation for a palliative care specialist to help you with managing symptoms and your quality of life.

Congratulations!

You have successfully completed the program: Managing Side Effects of Treatment for Metastatic Breast Cancer: You're Not Alone