Carcinoma of unknown primary is a diagnosis healthcare professionals give when they can't find where a cancer started. A carcinoma of unknown primary is an advanced cancer that has spread in the body.

Most often, health professionals detect a cancer when it grows in the place where it started. The place where a cancer started growing is called the primary cancer. Sometimes health professionals first detect a cancer when it spreads. When cancer spreads it's called metastatic cancer.

In carcinoma of unknown primary, healthcare professionals find the metastatic cancer. But they can't find the primary cancer. Carcinoma of unknown primary also is called occult primary cancer.

Healthcare teams often use the kind of primary cancer you have to help decide on the treatment. If you're found to have carcinoma of unknown primary, this piece of information is missing. Your healthcare team will work to find out what kind of cancer you have.

Signs and symptoms of carcinoma of unknown primary include:

• A cough that won't go away.
• Feeling very tired.
• Fever that doesn't have a clear cause.
• Losing weight without trying.
• Nausea and vomiting.
• Pain in one part of the body.
• Swelling of the belly.
• Swollen lymph nodes.

When to see a doctor

Make an appointment with a doctor or other healthcare professional if you have any symptoms that worry you.

The cause of carcinoma of unknown primary often isn't known. Healthcare professionals use this diagnosis when they find signs of cancer that has spread but can't find where the cancer started. The place where a cancer started growing is called the primary cancer.

Carcinoma of unknown primary can happen if:

• The primary cancer is too small to detect with imaging tests.
• The primary cancer was killed by the body's immune system.
• The primary cancer was removed in an operation for another condition.

The risk of carcinoma of unknown primary might be related to:

• Older age. This type of cancer happens most often in people older than 60.
• Family history of cancer. If a close relative had carcinoma of unknown primary, you may have an increased risk of this cancer. There also is some evidence that carcinoma of unknown primary happens more often in people with a family history of cancer that affects the lungs, kidneys or colon.
• Smoking cigarettes. People who smoke cigarettes may have a higher risk of carcinoma of unknown primary.

To diagnose carcinoma of unknown primary, a healthcare professional might start by examining your body. Other procedures might include imaging tests and a biopsy. If your healthcare team finds carcinoma of unknown primary, they'll do other tests to find the place where the cancer started.

Physical exam

A healthcare professional might examine your body to better understand your symptoms.

Imaging tests

Imaging tests make pictures of the body. They can show the location and size of the cancer. Imaging tests might include:

• Computerized tomography scan, also called CT scan.
• Magnetic resonance imaging, also called MRI.
• Positron emission tomography scan, also called PET scan.

Biopsy

A biopsy is a procedure to remove a sample of tissue for testing in a lab. In the lab, tests can show whether cells in the tissue are cancerous. Other tests can show the kind of cells involved in the cancer. In carcinoma of unknown primary, tests show that the cancer cells spread from somewhere else.

Tests to look for the primary cancer

If a biopsy finds cells that spread from somewhere else, your healthcare team works to find where they started. The place where a cancer started growing is called the primary cancer.

Tests to find the primary cancer might include:

• Physical exam. A healthcare professional might do a full body exam to look for signs of cancer.
• Imaging tests. Imaging tests might include CT and PET scans.
• Organ function tests. Blood tests that measure organ function tell the healthcare team how well the organs are working. The results might give the team clues about whether cancer might be affecting certain organs, such as the kidneys and liver.
• Tumor marker tests. Some cancers release proteins that can be detected in the blood. Tests to detect these proteins, called tumor marker tests, might help find the primary cancer. Examples of tumor marker tests include prostate-specific antigen test for prostate cancer and cancer antigen 125 test for ovarian cancer.
• Testing cancer cells in the lab. Healthcare professionals in the lab might run more tests on the cancer cells to get more clues about where they started.

Sometimes these tests can find the primary cancer. If this happens, you no longer have carcinoma of unknown primary. For some people, the primary cancer is never found. If this happens, your healthcare team will use information from all of your tests to make a treatment plan.

Treatment for carcinoma of unknown primary often involves medicines. Cancer treatments that use medicines include chemotherapy, immunotherapy and targeted therapy. Carcinoma of unknown primary is a cancer that has spread in the body. Cancer medicines can travel through the body and kill cancer cells. Sometimes healthcare professionals use other treatments, such as surgery and radiation therapy.

Chemotherapy

Chemotherapy treats cancer with strong medicines. Many chemotherapy medicines exist. Most chemotherapy medicines are given through a vein. Some come in pill form.

Immunotherapy

Immunotherapy for cancer is a treatment with medicine that helps the body's immune system kill cancer cells. The immune system fights off diseases by attacking germs and other cells that shouldn't be in the body. Cancer cells survive by hiding from the immune system. Immunotherapy helps the immune system cells find and kill the cancer cells.

Targeted therapy

Targeted therapy for cancer is a treatment that uses medicines that attack specific chemicals in the cancer cells. By blocking these chemicals, targeted treatments can cause cancer cells to die.

Radiation therapy

Radiation therapy treats cancer with powerful energy beams. The energy can come from X-rays, protons or other sources. During radiation therapy, you lie on a table while a machine moves around you. The machine directs radiation to precise points on your body.

Radiation therapy might be used for carcinoma of unknown primary that's only in a few areas of the body. It also can be used to help control symptoms, such as a growing cancer that's causing pain.

Surgery

Surgery to cut away the cancer might be used for carcinoma of unknown primary that's only in one area. Healthcare teams might use surgery to remove cancer cells in the liver or in the lymph nodes.

Palliative care

Palliative care is a special type of healthcare that helps people with serious illnesses feel better. If you have cancer, palliative care can help relieve pain and other symptoms. A team of healthcare professionals give palliative care. This can include doctors, nurses and other specially trained professionals. Their goal is to improve the quality of life for you and your family.

Palliative care specialists work with you, your family and your care team to help you feel better. They provide an extra layer of support while you have cancer treatment. You can have palliative care at the same time as strong cancer treatments, such as surgery, chemotherapy or radiation therapy.

When palliative care is used along with other treatments, people with cancer may feel better and live longer.

Coping with carcinoma of unknown primary often involves learning to cope with distress. Many people with this cancer have distress. Symptoms of distress include being worried, scared, sad or angry about your cancer. These feelings can happen because this diagnosis comes with many questions. A person with carcinoma of unknown primary may have many tests and never know exactly where the cancer started. Sometimes it's not clear which treatment is the best.

With time, you'll find what helps you cope with feelings such as distress and others. Until then, here are some ideas for coping.

Learn enough about cancer to make decisions about your care

Ask your healthcare team about your cancer, including your test results, treatment options and, if you like, your prognosis. As you learn more about cancer, you may become more confident in making treatment decisions.

Keep friends and family close

Keeping your close relationships strong will help you deal with your cancer. Friends and family can provide the practical support you'll need, such as helping take care of your home if you're in the hospital. And they can serve as emotional support when you feel overwhelmed by cancer.

Find someone to talk with

Find a good listener who is willing to hear you talk about your hopes and fears. This may be a friend or family member. The concern and understanding of a counselor, medical social worker, clergy member or cancer support group also may be helpful.

Ask your healthcare team about support groups in your area. In the United States, other sources of information include the National Cancer Institute and the American Cancer Society.

Make an appointment with a doctor or other healthcare professional if you have any symptoms that worry you. If your healthcare professional thinks that you might have cancer, you may be referred to a specialist. Often this is a doctor who specializes in caring for people with cancer, called an oncologist.

Here's some information to help you get ready for your appointment.

What you can do

When you make the appointment, ask if there's anything you need to do in advance, such as fasting before having a specific test. Make a list of:

• Your symptoms, including any that seem unrelated to the reason for your appointment.
• Key personal information, including major stresses, recent life changes and family medical history.
• All medications, vitamins or other supplements you take, including the doses.
• Questions to ask your doctor.

Consider bringing a family member or friend to help you remember the information you're given.

For carcinoma of unknown primary, some basic questions to ask your doctor include:

• What's likely causing my symptoms?
• Other than the most likely cause, what are other possible causes for my symptoms?
• What tests do I need?
• What's the best course of action?
• What are the alternatives to the primary approach you're suggesting?
• I have other health conditions. How can I best manage them together?
• Are there restrictions I need to follow?
• Should I see a specialist?
• Are there brochures or other printed material I can have? What websites do you recommend?

Don't hesitate to ask other questions.

What to expect from your doctor

Your doctor is likely to ask you several questions, such as:

• When did your symptoms begin?
• Have your symptoms been continuous or occasional?
• How severe are your symptoms?
• What, if anything, seems to improve your symptoms?
• What, if anything, appears to worsen your symptoms?