Patients with 'cancer of unknown primary origin' have metastatic malignant disease without an identifiable primary site.
For patients with this condition the type of tumour, the extent of its spread, and the outcome of treatment all vary widely. Most patients have malignancy that appears to derive from epithelial cells, that is, 'carcinoma of unknown primary origin' (CUP).
CUP is currently an inexact term because it is often applied to patients who have had only limited investigations. Patient who presents with metastatic malignancy (in the form of tumour masses or effusions) identified on clinical examination or by imaging, without an obvious primary site, is regarded as having "malignancy of undefined primary origin
"Provisional carcinoma of unknown primary origin
" (provisional CUP) is used to refer to patients with metastatic malignancy of proven epithelial, neuroendocrine or undifferentiated lineage, after initial, but not exhaustive investigations. Although a primary site will be found in most of these patients, or a non-epithelial malignancy diagnosed, in some patients a primary site will not be found and a diagnosis of "provisional CUP
" will change to a diagnosis of "confirmed CUP
" after the results of all tests are complete.
Adapted from Diagnosis and management of metastatic malignant disease of unknown primary origin. National institute for Health and Clinical Excellence (NICE) Guideline July 2010. Internet. Accessed on July 4, 2016.