Overview
Carcinoma of unknown primary is a diagnosis given when doctors aren't able to locate where a cancer began.
Most often, cancer is diagnosed when doctors discover the spot where the cancer began (primary tumor). If the cancer has spread (metastasized), those sites might be discovered, too.
In carcinoma of unknown primary, also known as occult primary cancer, doctors find the cancer cells that spread in the body, but they can't find the primary tumor.
Doctors consider the location of the primary tumor when choosing the most appropriate treatments. So if carcinoma of unknown primary is found, doctors work to try to identify the primary tumor site. Your doctor might consider your risk factors, symptoms, and results from exams, imaging tests and pathology tests when trying to determine where your cancer began.
Symptoms
Signs and symptoms of carcinoma of unknown primary depend on what part of the body is involved. In general, they might include:
- A lump that can be felt through the skin
- Pain
- Changes in bowel habits, such as new and persistent constipation or diarrhea
- Frequent urination
- Cough
- Fever
- Night sweats
- Losing weight without trying
Causes
In general, cancer forms when cells develop changes (mutations) in their DNA. The DNA contains instructions that tell cells what to do. Certain mutations can cause a cell to multiply uncontrollably and to continue living when normal cells would die. When this happens, the abnormal cells accumulate and form a tumor. The tumor cells can break away and spread (metastasize) to other parts of the body.
In carcinoma of unknown primary, the cancer cells that spread to other parts of the body are found. But the original tumor isn't found.
This can happen if:
- The original cancer is too small to be detected by imaging tests
- The original cancer was killed by the body's immune system
- The original cancer was removed in an operation for another condition
Risk factors
The risk of carcinoma of unknown primary might be related to:
- Older age. This type of cancer is most likely to occur in people older than 60.
- Family history of cancer. There's some evidence that carcinoma of unknown primary might be associated with a family history of cancer that affects the lungs, kidneys or colon.
Oct. 06, 2022
FAQs
Symptoms and Causes
What is the cause of unknown primary cancer? ›
Causes of cancer of unknown primary
Smoking may be an important risk factor, as more than half of cancer of unknown primary patients have a history of smoking. Other risk factors may include older age, diet, alcohol and obesity - common risk factors for many cancers.
What is the life expectancy of someone with cancer of unknown primary? ›
Generally for all those with CUP: around 16 out of 100 people (around 16%) survive for 1 year or more.
What is cancer of unknown primary source? ›
Carcinoma of unknown primary origin (CUP) is a diverse group of cancers that is defined by the presence of metastatic disease with no identified primary tumor at initial presentation. CUP has been reported to comprise approximately 2% to 5% of all cancer cases.
Is cancer of unknown primary always stage 4? ›
There is no staging system for cancer of unknown primary (CUP). This is because the cancer has already spread and doctors don't know where the original cancer started.
What is the most common type of cancer of unknown primary? ›
Adenocarcinomas: About six of every 10 cancer of unknown primary cases are adenocarcinomas, meaning they began in gland cells. Most frequently, the primary sites are the lung, pancreas, breast, prostate, stomach, liver or colon.
How to treat cancer of unknown primary? ›
The main treatment for cancer of unknown primary (CUP) is cancer drugs, most commonly chemotherapy. You often have a combination of 2 or 3 chemotherapy drugs. You may also have radiotherapy to help to control your symptoms and hormone therapy.
Can cancer of unknown primary go into remission? ›
However, complete cure remains a very rare event in CUP. Remission can be achieved with a platinum-containing regimen combined with radiotherapy.
Is cancer of unknown primary hereditary? ›
There's some evidence that carcinoma of unknown primary might be associated with a family history of cancer that affects the lungs, kidneys or colon.
How do you find unknown primary cancer? ›
You may have x-rays or scans to help find a primary cancer, or understand more about the type of cancer you have. We have more information about x-rays, mammograms, CT scans, PET-CT scans, MRI scans, and ultrasound scans in our A-Z of tests.
Carcinoma of unknown primary (CUP) is a rare disease in which malignant (cancer) cells are found in the body but the place the cancer began is not known. Sometimes the primary cancer is never found. The signs and symptoms of CUP are different, depending on where the cancer has spread in the body.
Where do primary cancers start? ›
The primary cancer is the place where a cancer starts growing. Cells from this primary site may break away and spread to other parts of the body through the bloodstream or lymphatic system. These escaped cells can then grow and form other tumours, which are known as secondary cancers or metastases.
How long can you live with cancer of unknown primary? ›
Because carcinoma of unknown primary (CUP) is not the primary cancer and has already spread when it was found, the potential to cure the cancer is less likely than finding a primary cancer early. Survival rates vary from person to person, ranging from months to several years.
What is the mortality rate for cancer of unknown primary? ›
Median survival in patients with cancer of unknown primary origin ranges from 11 weeks to 11 months. The 5-year overall survival rate is about 11%.
What is a cancer that has no symptoms? ›
Silent cancers are cancers that do not have any noticeable early symptoms, and in such cases, patients may have no symptoms of cancer until the advanced stages. The doctor diagnoses silent cancers, usually in their advanced stages.
What happens if they can't find a primary cancer source? ›
Your doctor may ask you to have several tests to try to find the primary cancer. If the tests cannot find where the cancer started, the doctor will try to identify the type of cell the cancer developed from. This gives the doctor a better idea of where the cancer may have started.
What are the risk factors for unknown cancer? ›
Some risk factors, such as family history and age, may not be in your control. But others like diet, sun exposure, weight, and tobacco use are things that you can change. Knowing cancer risk factors can help you make choices that might help lower your overall cancer risk.
