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CANCER OF UNKNOWN PRIMARY FOUNDATION

OnHealthy

Cancer Of Unknown Primary (CUP)

When a person is diagnosed with cancer that has spread within the body (metastatic cancer) the primary site – the place in the body where the cancer started –  is not always obvious. Finding the genetic origin of the cancer is important to define the best treatment. When the origin of the cancer is not identified with confidence, after initial tests, this is described as Cancer of Unknown Primary or CUP.

In the UK about 8,000 people are diagnosed with CUP each year – that is about 22 every day. CUP is the 15th most frequent cancer diagnosis (the 11th most common cancer for women and the 15th most common for men). It is the 6th commonest cause of cancer death in the UK. In the last decade CUP incidence and mortality rates in the UK have seen c. 34%  reduction in incidence and c.29% reduction in mortality.   [CRUK stats using average of 2017-19 data as @ Jan 2025].

The number of people diagnosed with CUP each year in the UK would fill about 60 large passenger jets such as the 737; yet most people have never heard of CUP and find it hard to believe that in this scientific age the cause of the cancer, and its spread, can remain unknown.

For many of those diagnosed initially with an undefined or uncertain metastatic cancer the origin of the cancer will be found through further tests. When the primary site/ tumour of origin remains truly unknown the cancer can be contained with treatment, but life expectancy is limited.

A cancer diagnosis is frightening for patient, family and friends. Not to know where this strange, invasive, disease has originated in the body is a double blow. CUP patients face unique psychological and social concerns.  We exist to offer information and support to CUP patients, their families and friends; whilst raising awareness of this problem to stimulate action that will improve treatment.

Please note: We are no longer a registered charity (reasons shown here) and unable to accept donations; but we are supporting CUP research through The Christie Hospital (see this page for CUP donations) and we continue to maintain this site as a source of information for patients, carers, clinicians and researchers.

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