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Cancer of Unknown Primary: Symptoms

One of the first symptoms of cancer of unknown primary (CUP) may be a swollen lymph node in your neck, underarm, or groin. 

What are the symptoms of cancer of unknown primary?

If you have CUP, your symptoms depend on where in your body the cancer forms. Symptoms may include:

Swollen lymph nodes

Lymph nodes are tiny, bean-sized organs that are part of the immune system. They help to fight infection. Cancer often spreads to lymph nodes. You may notice swollen or firm lymph nodes. Or a healthcare provider may find them during a routine check-up. Enlarged lymph nodes are most commonly noticed in the neck, above your collarbone, under your armpits, or in your groin.

Pain in your bones

If cancer has spread to the bone, you may have bone pain. The bone may also become weak and may break easily. The bones most often affected are the back, legs, and hips.

Chest or stomach pain or fullness

These symptoms can be caused by tumors pressing on internal organs. They may also happen if the cancer is growing in your liver. This can also cause bloating and yellowing of your skin and whites of your eyes (jaundice). These symptoms may also start if cancer grows on the surface of other organs in your belly (abdomen). This can cause extra fluid to build up in your abdomen. 

Poor appetite or weight loss, fatigue, or weakness

These symptoms may be signs that cancer has spread to your bone marrow or digestive tract.

Tumors on your skin

Tumors that start in organs inside your body can spread to your skin. It can cause bumps and nodules on your skin. Sometimes, tumors that spread to your skin are the first sign of CUP.

Shortness of breath or a persistent cough

If cancer is in your lungs, you may feel short of breath when doing everyday tasks like walking, eating, or talking.


Cancers that start in the digestive tract can cause slow bleeding. It can lead to low red blood cell levels (anemia). Cancer of any type can suppress bone marrow activity. This may result in anemia, too.

Confusion, headache, blurry vision, vomiting, and seizures

These can be signs of a brain lesion. In rare cases, this is the only site of a hidden cancer in the body.

Other symptoms of CUP are also possible. Symptoms depend on where the cancer started. Keep in mind that all these symptoms can be, and are likely to be, caused by health issues other than cancer.

Fever or night sweats

Fever for an unknown reason that doesn't go away can be a sign of CUP, so are night sweats. These may soak your bedclothes and sheets.

Bowel or bladder changes

Ongoing constipation, diarrhea, frequent urination, or trouble passing urine can be caused be cancer that's spread to these organs or tumors causing pressure in the belly (abdomen).

When to see your healthcare provider

If you notice any of these symptoms, see a healthcare provider right away. Many of these symptoms may be caused by other health issues. But only a healthcare provider can tell if you have cancer.

Online Medical Reviewer: Kimberly Stump-Sutliff RN MSN AOCNS
Online Medical Reviewer: L Renee Watson MSN RN
Online Medical Reviewer: Preeti Sudheendra MD
Date Last Reviewed: 3/1/2021
© 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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