Are side effects taking a toll on your life?

The right dose for the right person

Medicines for metastatic breast cancer (MBC) often come with side effects. But, did you know that many drugs that treat MBC can be just as effective at a lower dose, with fewer side effects? This approach to customizing your treatment regimen is called patient-centered dosing.

Talk with your provider about your side effects, what you like to do, and whether the medicines you take can be adjusted. Your care team can help find a dose and schedule for your medicines that is right for you.

Keep doing what you love

Side effects affect different people in different ways. When you start a new treatment, tell your doctor what’s important in your life. For example, your goal might be to work, have lunch dates with friends, travel, or play with children or grandchildren.

Talk to your team about any side effects that prevent you from thriving, such as:

• Diarrhea or constipation
• Fatigue
• Headache
• Mouth sores
• Redness, swelling, or pain in your hands and/or feet (hand-foot syndrome)

Learn more about treatments for MBC.

Standard doses are a starting place

Medicines for MBC are studied and approved for use at a dose that’s been proven to work. This becomes the standard dose, and your doctor is most likely to start there to give you the best chance of success. If side effects are interfering with your daily life or things you want to do, then adjustments may be possible.

When you’ve been through difficult cancer treatments, it can feel normal to push through discomfort without complaining. But, over time, you may be able to stay on a drug for longer if you can find a dose that works while allowing you to do things that you enjoy.

While some side effects are to be expected, you should tell your care team how your medicine is affecting you. Side effects may even be an early sign that a medicine should be discontinued, whether because of side effects or other long-term medical issues. Your oncologist can help you figure out what to expect and if a change is right for you. Never make treatment adjustments without your doctor’s approval.

Often, a lower, but still effective, dose may also allow you to keep taking a medicine for a longer time, which is important. Sometimes, other adjustments may be helpful. Talk with your doctor about taking your medicine at a different time of day or changing the rate of infusion, or you might ask about a temporary pause from your medication for a short “treatment holiday.” The earlier you bring it up, the sooner you can start feeling better.

Medicines that can be adjusted

Some breast cancer medicines that commonly cause side effects and can be considered for patient-centered dosing adjustments include, but are not limited to:

• Antibody-drug conjugates: sacituzumab govitecan (Trodelvy), trastuzumab deruxtecan (Enhertu)
• CDK 4/6 inhibitors: abemaciclib (Verzenio), palbociclib (Ibrance), ribociclib (Kisqali)
• mTOR inhibitors: everolimus (Afinitor)
• Chemotherapy: capecitabine (Xeloda), paclitaxel (Taxol), gemcitabine, carboplatin, eribulin

Dosing terms to know

Patient-centered dosing
Adjusting dose or schedule to reduce side effects while keeping treatment working against cancer.

Dose reduction
Lowering the amount of medicine to help manage side effects safely.

Dose modification
Changing dose, timing, or schedule to better support safety and treatment benefit.

Biomarker
A feature of your cancer cells or tumor that helps guide treatment decisions.

Targeted therapy
Treatment designed to attack specific features of cancer cells.

Estrogen receptor (ER)
A protein on some breast cancer cells that helps them grow using estrogen.

Progesterone receptor (PR)
A protein on some breast cancer cells that helps them grow using progesterone.

Hormone receptor (HR)
Breast cancer that tests positive for estrogen or progesterone receptors. [See ER; PR.]

Early-stage breast cancer (ES)
Breast cancer that has not spread beyond the breast or nearby lymph nodes (stages 0, I, II, or III).

HER2 receptor (HER2)
A protein on the surface of breast cancer cells. The amount of these receptors helps decide if certain treatments can be used that target those proteins.

Metastatic breast cancer (MBC)
Also known as stage IV breast cancer, this is breast cancer that has spread to other distant parts of the body, like the bones or other organs.

De novo metastatic breast cancer
Breast cancer diagnosed as stage IV without a prior early-stage diagnosis.

Aromatase inhibitor (AI)
A pill that lowers estrogen levels to treat hormone receptor-positive breast cancer. [See HR.]

Ovarian suppression (OS)
Treatment like Zoladex or Lupron, which stops the ovaries from making estrogen.

Chemotherapy
Medicine that kills or slows fast-growing cancer cells.

Antibody drug conjugate (ADC)
A targeted treatment that delivers chemotherapy directly to cancer cells. [See Targeted therapy; Chemotherapy.]

CDK 4/6 inhibitor
A class of targeted medicine that slows cancer cell growth in some hormone receptor-positive cancers. [See HR.]

Immunotherapy
Treatment that helps your immune system recognize and attack cancer cells.

Checkpoint inhibitor
A type of immunotherapy that removes barriers blocking immune cells from attacking cancer. [See Immunotherapy.]

Side effects
Physical or emotional symptoms caused by cancer treatment.

Treatment effectiveness
How well a treatment controls, shrinks, or slows cancer.

Dose delay
Postponing treatment briefly so your body can recover from side effects.

Quality of life
Your overall comfort, emotional well-being, and ability to do your preferred daily activities during treatment.

Maximum tolerated dose (MTD)
The highest dose of a treatment most people can take without severe side effects.

Dose optimization
Choosing the safest, most effective dose rather than automatically using the highest approved dose.

Shared decision-making
When you and your doctor work together to choose the best treatment plan for you.

Clinical trial phase (Phase I)
An early research stage that studies safety and helps determine the best treatment dose.

Recommended starting dose (RSD)
The dose doctors usually begin with based on how the treatment was studied.

Start the conversation

If you are experiencing side effects that are getting in the way, make a plan for your next appointment with your doctor. Write down your questions and concerns ahead of time.

Check out the Patient-Centered Dosing Initiative’s conversation guide >>>

Tips for talking with your care team about side effects:

• Use a journal or a symptom-tracking app to keep a record of how you feel. Try to write down when side effects occurred and what helped or didn’t help. Share this information during your next visit.
• Use your patient portal to write short updates to your care team. For example: “I’m on day 4 and having this problem. If it doesn’t get better by next week, I’ll call the office.”
• If your regular visit is short, ask to make a special appointment just to talk about side effects.
• Bring a trusted person with you to your appointments where you discuss your quality of life. They can help take notes, provide emotional support, and help make sure your questions are answered.
• Get a second opinion about your treatments annually, especially if you are not having treatment at a major cancer center. A second opinion can help confirm that you are receiving the most effective treatments with the fewest side effects.
• Be honest with your doctor to help them understand what you hope to get out of treatment. Partner with your treatment team by communicating early and often.

When you get to your appointment, try these conversation starters:

• I want to live as long as possible, but I also want to live as well as possible. What are my options for reducing side effects?
• I want to live well while taking this medicine, but my side effects are getting in the way of activities that are important to me. Can you suggest ways to help me reach my goals?