Cancer of unknown primary

Malignancy of unknown origin (MUO) is when we suspect that you might have cancer but we are not certain. This is usually in response to finding an area of abnormality on a scan or blood test. Our primary task is to find out whether or not you have cancer.

Having a suspicion of cancer can be very worrying. You may feel that there is a lot of waiting and uncertainty. There may be different tests that we need to complete before we are able to give you answers as to whether you have cancer, or what type of cancer you have.   

For the majority of patients, we are able to clearly determine where the cancer has started. However, sometimes we find evidence that a cancer has spread around the body without being able to clearly determine a starting point.

If we are able to clearly determine the source of your cancer, your care will transfer to the appropriate specialist team. For example, if we believe your cancer has started in the lung, you will be treated by the lung cancer team.

Sometimes, on the basis of tests and biopsy, if we are still unable to identify where the cancer has started, your formal diagnosis will be cancer of unknown primary (CUP), and your care will be under a specialist CUP consultant.