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Cancer of Unknown Primary: Treatment Choices

Learning about your treatment options

You may have questions and concerns about your treatment options. You may want to know how you’ll feel, how you'll look, and how your body will work after treatment. You may also wonder if you’ll have to change your normal activities.

Because cancer of unknown primary (CUP) can be linked to many different types of cancers, there's no 1 way to treat it. The treatment your healthcare provider suggests depends on where the cancer most likely started. It also depends on the size of the tumor, its location, the results of lab and imaging tests, and the stage or extent of the cancer. Your age and overall health are also taken into account.

Today there are many ways to find the origin of CUP. These include genetic testing and antibody testing of the cancer cells. The closer your healthcare provider can get to finding where the cancer came from (called the primary site), the better the chance that treatment will work.

It’s normal to have questions and concerns about treatment. Learn all you can about the cancer and your treatment choices. That way, you’ll be able to help make decisions about your care.

Your healthcare provider is the best person to answer questions about treatment. They can explain what your treatment choices are, how well treatment is expected to work, and what the risks and side effects may be.

You may want to ask:

  • Where is the tumor? How big is it?

  • Do you have any idea where the cancer started?

  • What are my treatment choices?

  • How well might treatment work?

  • What's the goal of treatment?

  • What are the risks and side effects?

  • How might treatment affect my normal activities? Will I be able to work? Take care of my home?

  • Will my insurance cover treatment? How much will I have to pay?

Sometimes, even if a cure isn’t possible, treatment may improve your quality of life. It may also help you live longer. Talk with your provider about the possible side effects and benefits of treatment.

It’s more important to make an informed choice rather than a quick choice. It may take a few weeks to get results from some tests. Make sure you get all the information you need before making your decision. You may want to have your partner, spouse, family, or friends be part of this process, too.

Types of treatment for CUP

Treatment is usually started only after trying to figure out the primary cancer. This means a lot of tests will be done, including imaging, blood, and other tests. Lab tests will be done to look for genetic mutations in the cancer cells to help find the primary cancer. 

When a primary cancer can’t be found, you’ll get treatment for CUP. It may be local, systemic, or both. Local treatments remove, destroy, or control cancer cells in 1 area. Radiation and surgery are local treatments. Systemic treatments are used to destroy or control cancer cells throughout your body. Chemotherapy and hormone therapy are systemic treatments.

You may get just 1 type of treatment or a combination of treatments.


Chemotherapy (or chemo) is the use of strong medicines that kill cancer cells. One goal of chemo is to shrink or slow the growth of the tumor. It can also help reduce the chance that the cancer will spread. This may ease symptoms or extend your life.

Radiation therapy

Radiation uses strong beams of energy to kill cancer cells and shrink tumors. It can be used to kill cancer in 1 part of the body. It can also be used to ease the symptoms of cancer. There are 2 kinds of radiation: external and internal. For external radiation, a machine directs radiation at the tumor from outside of the body. For internal radiation, a radioactive source (often in tiny pellets) is put in or near the cancer. This kills the cells close to the source.

Hormone therapy

This treatment keeps certain hormones in the body from helping some types of cancer cells to grow. Stopping the hormones can be done different ways. You may have surgery or radiation. This is done to take out or destroy the organ(s) that make hormones, like the ovaries or testicles. Another option is getting medicines that lower hormone levels or make the cancer cells unable to use them.


The goal of surgery is to remove cancer from your body. Because CUP has already spread when it's found, it's not always helpful.

Clinical trials for new treatments

Experts are always finding new ways to treat cancer. These new methods are tested in clinical trials. Taking part in a clinical trial means you get the best treatment available today, and you might also get new treatments that are thought to be even better. Before starting treatment, ask your healthcare team if there are any clinical trials you should think about. Because CUP is rare and often hard to treat, many healthcare providers advise treatment in a clinical trial.

Working with your healthcare provider

At first, thinking about treatment options may seem overwhelming. Talk with your healthcare team and loved ones. Make a list of questions. Consider the benefits and possible side effects of each option. Discuss your concerns with your healthcare provider before making a decision.

Ask your healthcare provider how much time you can take to explore your options. It can be tough to decide on a treatment. You may want to get a second opinion first. A second opinion can help give you peace of mind. It can also help you be sure that you’re making the best choices for treatment. You may want to talk with your family and friends, too.

Online Medical Reviewer: Kimberly Stump-Sutliff RN MSN AOCNS
Online Medical Reviewer: L Renee Watson MSN RN
Online Medical Reviewer: Todd Gersten MD
Date Last Reviewed: 4/1/2021
© 2022 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.
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