Risks and causes of cancer of unknown primary (CUP) | Cancer Research UK
Cancer Research UK on Google+ Cancer Research UK on Facebook Cancer Research UK on Twitter

Risks and causes of cancer of unknown primary (CUP)

Men and woman discussing unknown primary cancer

This page tells you about the risks and causes for cancer of unknown primary (CUP).

 

A quick guide to what's on this page

Risks and causes of cancer of unknown primary (CUP) 

About 3 out of every 100 cancers diagnosed (3%) in the UK are unknown primary cancers, where the specialist cannot tell where the cancer started. It is a more common situation than many people realise.

We cannot be specific about the possible causes or risk factors of unknown primary tumours, because we don't know what type of cancer it is. Different cancers are caused by different things. Smoking most often causes lung cancer and the sun causes skin cancer, for example. There is detailed information about what causes cancer in our section about cancer.

Being diagnosed with any type of cancer is difficult to accept. You may find yourself spending a lot of energy trying to work out what caused your unknown primary cancer. But it may not be possible to find out. It may help to focus instead on getting through your treatment and staying as well as you can.

 

CR PDF Icon You can view and print the quick guides for all the pages in the About CUP section.

 

 

How common unknown primary tumours are

About 9,600 people are diagnosed with cancer of unknown primary each year in the UK. That is about 3 out of every 100 cancers diagnosed (3%). It is a more common situation than many people realise. Cancer of unknown primary can develop at any age but it is more common in people over the age of 65. 

 

General causes of cancer

Cancer is not one single disease. There are more than 200 different types of primary cancer. We can't be specific about the possible causes or risk factors of unknown primary tumours, because we don't know which type of cancer it is. Each type of cancer has different causes – for example, smoking most often causes lung cancer and the sun most often causes skin cancer.

Generally speaking, cancer is a disease caused by many different things coming together, rather than one single thing. Many of us have a combination of genes that make it more likely that we will develop a cancer than get heart disease, for example. If you have this genetic make up, you may still not get cancer. But if you eat a diet that makes cancer more likely, or you smoke, then your chances of getting it will be increased further.

Many cancers of unknown primary are later found to be cancers that are often related to smoking – for example, cancer in the lung, pancreas, kidney, larynx (voice box), and oesophagus (food pipe). Stopping smoking is always a good way to lower your cancer risk. Other ways to reduce risk are to make sure you eat a healthy diet and be aware of the possibility of sun damage to your skin.

 

Where to find more information about causes

Our about cancer section includes a general overview of what causes cancer, a page about diet and cancer and a page about your environment and cancer. There is also a page called why don't we all get cancer?

 

How you may feel

It is quite common for people diagnosed with cancer to feel strongly that they must find out what caused it. Unfortunately, we don't always know. In some people with cancer of unknown primary, the primary cancer type is never found.

Cancer can just happen because of bad luck. Over years, a cell gathers changes to its genetic code (DNA) that eventually make it become cancerous. A cancer causing chemical such as nicotine may trigger one or two of the changes. But often, something just goes wrong in the DNA of the cell by itself – a bit like a spelling mistake in the code. The cancer cell then begins to grow and divide much more quickly than normal cells. The overgrowth of cells forms a tumour.

Being diagnosed with any type of cancer is difficult to accept and you may find yourself spending a lot of energy trying to work out what caused it. But sometimes the cause is never found. Everyone copes with this in their own way. You may find it helpful to focus on putting your energy into getting through your treatment and staying as well as you can.

Rate this page:
Submit rating

 

Rated 4 out of 5 based on 3 votes
Rate this page
Rate this page for no comments box
Please enter feedback to continue submitting
Send feedback
Question about cancer? Contact our information nurse team

No Error

Updated: 15 July 2014