Cancers of unknown primary site: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up

definition, incidence and biologyCancers of unknown primary site (CUPs) represent a heterogeneous group of metastatic tumours for which a standardised diagnostic work-up fails to identify the site of origin at the time of diagnosis. CUPs account for 3%–5% of all malignancies. The unique biology of these tumours remains almost unknown [1.Massard C. Loriot Y. Fizazi K. Carcinomas of an unknown primary origin—diagnosis and treatment.Nat Rev Clin...