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Cancer of Unknown Primary: Treatment Choices

Learning about your treatment options

Because a cancer of unknown primary (CUP) can be any 1 of many types of cancers, there's no 1 way to treat it. The treatment your healthcare provider advises depends on where the cancer most likely started. It also depends on the size and location of the tumor or tumors, the results of your lab and imaging tests, and the stage or extent of the cancer. Your healthcare provider also takes your age and general health into account when advising treatment.

Today there many ways to find the origin of CUP. These include genetic analysis 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. 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 2 or 3 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 family and friends be part of this process.

Types of treatment for CUP

Treatment is usually started only after trying to figure out the primary cancer. This means you'll have a lot of tests, including imaging, blood, and other tests. Lab tests will be done to analyze genetic mutations in the cancer cells to look for a likely 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 entire body. Chemotherapy and hormone therapy are systemic treatments.

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


Chemotherapy is the use of medicines that kill cells that divide quickly, like cancer cells. The goals of chemotherapy are to shrink or slow the growth of the cancer. It can also help reduce the chance that the cancer will spread. This may ease symptoms or extend your life. In some cases, it may cure the cancer.

Radiation therapy

The goal of radiation is to kill cancer cells. It does this by using beams of energy. Radiation can be used to kill a 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) are put in or near the cancer. This kills the cells close to the source.

Hormone therapy

This treatment stops the hormones in the body from allowing certain 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. These include the ovaries or testicles. Another option is getting medicines that lower hormones 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 finding new ways to treat cancer. These methods are tested in clinical trials. Before starting treatment, ask your healthcare team if there are any clinical trials you should consider. Because CUP is rare and often hard to treat, many healthcare providers advise treatment in a clinical trial.

Working with your healthcare provider for a treatment plan

Work with your healthcare team to make a treatment plan. It may take time to choose the best plan.

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 give peace of mind. It can also help you be sure that you’re making the best choices for treatment. You may also want to talk with your family and friends.

Online Medical Reviewer: Kimberly Stump-Sutliff RN MSN AOCNS
Online Medical Reviewer: Lu Cunningham
Online Medical Reviewer: Richard LoCicero MD
Date Last Reviewed: 3/1/2019
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