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Cancer of Unknown Primary: Chemotherapy

What is chemotherapy?

Chemotherapy (chemo) is the use of strong medicines to kill cancer cells. The medicines travel all through your body in your bloodstream. They attack and kill cells that grow quickly, like cancer cells. Some normal cells also grow quickly. Because of this, chemo can harm those cells. This can cause side effects.

Man sitting in chair having infusion treatment.

When might chemotherapy be used for cancer of unknown primary?

Chemo medicines travel throughout your body. This makes chemo useful to treat cancer of unknown primary (CUP). It can kill cancer cells that may not have even been found on tests or scans.

Chemo can stop cancer cell growth, slow cell growth, or kill the cancer cells. It can shrink tumors. It can also help ease symptoms the cancer is causing. It may even make some tumors go away. In some cases, it can help people live longer.

How is chemotherapy given for cancer of unknown primary?

You might get chemo for CUP as a pill you swallow. Or it may be a liquid that's put right into your blood through a vein (IV). Then the medicine spreads through your body to kill cancer cells.

IV chemo treatment may be done as an outpatient visit to a hospital. This means you go home the same day. Or it may be done at your healthcare provider’s office, a chemo clinic, or in your home. In some cases, you may stay in the hospital during treatment.

You get chemo in cycles over a period of time. That means you get 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 have several cycles. Having treatment in cycles helps by:

  • Killing more cancer cells. The medicine can kill more cancer cells over time, because cells aren't all dividing at the same time. Cycles allow the medicine to fight more cells.

  • Giving your body a rest. Treatment is hard on other cells that divide quickly. This includes cells in the lining of your mouth and stomach. This causes side effects, like mouth sores and upset stomach. Between cycles, your body can heal and get a rest from the chemo.

  • Giving your mind a rest. Getting chemo can be stressful. Taking breaks between cycles can let you get an emotional break between treatments.

What chemo medicines are used to treat CUP?

The chemo medicine you get depends on your overall health and what's known about the cancer cells based on tests that have been done. For instance, it depends on what subtype of CUP it is, how fast the cancer is growing, where it is in your body, and if certain changes are found in the cancer cells.

In most cases, two or more chemo medicines are used at the same time. This is called combination chemo. The chemo medicines most often used to treat CUP include:

  • Paclitaxel

  • Cisplatin

  • Carboplatin

  • Docetaxel

  • Fluorouracil

  • Gemcitabine

  • Oxaliplatin

  • Capecitabine

  • Irinotecan

  • Leucovorin

What are common side effects of chemotherapy?

Chemo damages both normal cells and cancer cells. Side effects depend on which medicines are used and how much.

Common side effects of chemo include:

  • Appetite loss

  • Diarrhea

  • Hair loss

  • Mouth sores

  • Nausea and vomiting

  • Extreme tiredness (fatigue)

Other common side effects are caused by decreased blood counts, such as:

  • A decrease in white blood cells. This puts you at a higher risk for infections. If you have a fever during chemo, tell your healthcare provider right away.

  • A decrease in platelets. This puts you at risk for bleeding. Tell your healthcare provider about any bleeding or easy bruising you have during chemo.

  • A decrease in red blood cells. This causes fatigue, weakness, and a lack of energy.

Many chemo side effects can be treated to keep them from getting worse. There may even be things you can do to help prevent some of them. Be sure to tell your healthcare provider about any side effects you have. Most side effects go away over time after treatment ends. But some may last longer or be permanent.

Ask your healthcare provider what short- and long-term side effects you should expect. Also ask what can be done to help prevent or ease side effects.

Working with your healthcare provider

It's important to know which medicines you're taking. Write down the names of your medicines. Ask your healthcare team how they work and what side effects they may cause.

Talk with your healthcare team about what symptoms to watch for and when to call them. For instance, chemo can make you more likely to get infections. You may be told to check your temperature and stay away from people who are sick. You may need to call if you have a fever or chills. Make sure you know what number to call with questions. Is there a different number for evenings, holidays, and weekends?

It may be helpful to keep a journal of your side effects. Write down any physical, mental, and emotional changes you notice. 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.

Online Medical Reviewer: Amy Finke RN BSN
Online Medical Reviewer: Jessica Gotwals RN BSN MPH
Online Medical Reviewer: Todd Gersten MD
Date Last Reviewed: 8/1/2023
© 2024 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare provider's instructions.