Cancer Of Unknown Primary
Cancer of Unknown Primary is often a difficult diagnosis and results from a protracted pathway to diagnosis. It affects 2% of cancer cases in the UK, with 8,589 cases each year between 2016-2018 (Cancer Research UK, 2023) and the average prognosis following CUP diagnosis is 9-12 months.
What is CUP?
It is defined as a rare disease in which malignant cells are found in the body but the primary site of the cancer is not known (National Cancer Institute, 2021). During the typical malignant process, cancer can develop in any body tissue and retains characteristics of the cells in the type of tissue from which the cancer originates. While this primary cancer can metastasise, these metastatic deposits are consistent with the primary tumour. For example,
In some cases, metastatic disease is detected but the primary site, despite multiple tests, is not found.