Chemotherapy (chemo) uses special medicines to kill cancer cells. The medicines attack and kill cells that grow quickly, such as cancer cells. Some normal cells also grow quickly. Because of this, chemo can also harm those cells. This can cause side effects.

Chemotherapy is a systemic treatment. This means the medicines travel through the body in the blood.

Chemo is not a common treatment for thyroid cancer.

It is sometimes given if you are getting radiation therapy. It may help the radiation work better when treating anaplastic thyroid cancer.

It may also be used for advanced thyroid cancer that doesn't respond to other treatments.

You get chemo in cycles over a period of time. That means you may take the medicine for a set amount of time and then you have a rest period. Each period of treatment and rest is one cycle. You may get several cycles.

Most people have chemo in an outpatient part of the hospital or at the healthcare provider's office. You go home the same day. In some cases, you may stay in the hospital during treatment.

The chemo medicines used to treat thyroid cancer are often given into the blood through a small, thin flexible tube called an IV (intravenous) catheter. Currently, the chemo medicine that works best, doxorubicin, is still much less effective than surgery and radioactive iodine therapy (RAI). Doxorubicin is typically used in anaplastic thyroid cancer which is an aggressive subtype of thyroid cancer. Targeted therapy medicines known as kinase inhibitors may be used to treat certain thyroid cancers. You might also be enrolled in a clinical trial of newer medicines. Molecular typing of the cancer will determine what targeted therapies may work best.

Chemotherapy attacks cells that are dividing quickly. This includes normal cells as well as cancer cells. Normal, quickly dividing cells can be found in the bone marrow, the hair follicles, and lining of the intestines and mouth. Damage to these normal cells is a common cause for side effects. Side effects will depend on the type and amount of medicine being taken.

Some of the more common short-term side effects from chemo include:

• Nausea and vomiting
• Mouth sores
• Constipation or diarrhea
• Hair loss
• Infections from low white blood cell counts
• Easy bruising or bleeding from low blood platelets
• Tiredness from low red blood cell counts
• Skin problems, such as dryness, rash, blistering, or skin that gets darker
• Tingling, numbness, or swelling in hands or feet

Most side effects will go away or get better between treatments and over time after treatment ends. You may also be able to help control some of these side effects. Tell your healthcare providers about any side effects you have. They can help you cope with them.

A more serious possible side effect of some chemo medicines is organ damage. This can include damage to the kidneys, liver, testicles, ovaries, brain, heart, or lungs. You will have blood tests and other tests done while you're getting chemo. This is to make sure your organs are working correctly and you aren't having harmful reactions to the medicine.

It's important to know which medicines you're getting. Write down your medicines and ask your healthcare team how they work and what side effects they might have.

Talk with your healthcare providers about what signs to watch out for and when you should call your healthcare team. For instance, chemo can make you more likely to get infections. Make sure you know what number to call with questions. Is there a different number for evenings and weekends?

It may be helpful to keep a diary of your side effects. Write down any physical, thinking, and emotional changes. A written list will make it easier for you to remember your questions when you go to your appointments. It will also make it easier for you to work with your healthcare team to make a plan to manage your side effects.