What is Cancer of Unknown Primary – worldcupawareness.org

What is CUP?

Primary cancer means where the cancer started. The part of the body where the cancer first started to grow is called the primary site. The cancer type is usually named after the part of the body where it first started to grow. For example, a cancer that starts in the lung is called a primary lung cancer.

A secondary cancer happens when cancer cells separate from a primary site and spread to another part of the body. The cancer cells travel through the blood or lymphatic system and form a new cancer somewhere else in the body.

A secondary cancer is also called a metastasis or metastatic cancer. It is made up of the same type of cancer cells that formed the primary cancer. For example, a cancer that starts in the lungs and spreads to the liver is made up of lung cancer cells, not liver cancer cells.

Cancer of unknown primary (CUP) means that your doctor is not sure where the cancer started. They have found a secondary cancer but have not been able to find the primary cancer. People with CUP sometimes have secondary cancer in more than 1 part of the body

With CUP, doctors cannot always tell which part of the body the cancer cells are from. But cancers are made up of different types of cells. These can be grouped based on the type of cells they are made up of. Knowing the type of cell can give the doctors a better idea about where the cancer may have started. This helps them to plan the best treatment.

Cancer of unknown primary (CUP) is when a secondary cancer is diagnosed, but doctors can’t tell where the primary cancer started. The secondary cancer is named after the primary cancer. For example, a cancer that starts in the lungs and spreads to the liver is still a lung cancer. The secondary cancer in the liver is made up of lung cancer cells and not liver cells.

Secondary cancers are also usually treated according to the primary cancer. Knowing where the cancer started helps the doctors to know what types of treatment to use for the secondary cancer. For example, a lung cancer that has spread to the liver will be treated using lung cancer treatments. It’s treated differently to a cancer that starts in the liver (primary liver cancer).

With CUP, the primary cancer isn’t known. This means that treatment choices are often more difficult to make. (Macmillan.org.uk)

For some patients the origin of the cancer will be found through further tests, however for many patients the primary cancer will never be identified and will remain unknown. A cancer diagnosis in itself is devastating for patients, families and friends, but for the cause of the cancer to be unknown is entirely overwhelming.

Patients diagnosed with CUP need expert coordinated multidisciplinary support, effective communication is vital between teams, patients and their families regarding treatment plans and tests.

Metastases can develop close to the primary tumor. Even so close that the metastasis surrounds the tumor, as it were. It is then difficult for the doctor to tell the difference between the primary tumor and the metastasis. The doctor thinks he or she only sees the metastasis. He or she does not know that the primary tumor is also located here.

The primary tumor is too small to find by the available diagnostics, such ultrasound, CT, MRI and PET scan.
The primary tumor has been successfully fought by the patient’s immune system, or has left the body through a natural route (may involve primary tumors in the digestive tract).

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Missie Tumor Onbekend
Fannius Scholtenstraat 69,
1051EV, Amsterdam,
The Netherlands

Sarah Jennifer Knott Foundation,
38 Belgrave Road,
Rathmines,
D06 HW222,
Republic of Ireland

Patient Leaflet SJK (English)

Australia booklet (English)

Macmillan Booklet (English)

PTO NL Booklet (Dutch)

NFK NL Booklet (Dutch)

Infobroschüre CUP (German)