Blood tests for cancer of unknown primary (CUP)

If you have cancer of unknown primary (CUP) you may have blood tests. These can help your doctors know which area of the body it might be helpful to scan.

Blood tests can help doctors find out:

  • how organs such as the liver and kidneys are working
  • the number of different blood cells you are producing (your full blood count).

If you have cancer of unknown primary (CUP) blood tests can help your doctors know which area of the body it might be helpful to scan. For example, if the liver or kidneys are not working properly your doctors may decide to scan those areas.

A low number of red blood cells (anaemia) may mean that there is some bleeding inside the body. This could be from a cancer in the bowel or stomach.

Tumour markers

Some cancers produce chemicals. These can sometimes be measured in the blood with a blood test. These chemicals are called tumour markers. High levels of a marker may suggest you have a certain type of cancer. But the marker levels can be high for reasons other than cancer. So high levels of a tumour marker does not definitely mean you have a certain type of cancer. You will have this blood test alongside other tests to find this out.

There are many different tumour markers your specialist may use. These may include the following: