Cancer of unknown primary site.

BACKGROUND: Cancer of unknown primary (CUP) is the diagnosis given to patients with metastatic cancer with no known site of origin.

OBJECTIVE: This review summarises the current knowledge regarding the epidemiology, diagnosis, treatment and care of CUP.

DISCUSSION: The incidence and mortality rates of CUP are declining in Australia. CUP was the twelfth most common cancer and fifth most common cause of cancer death in 2011. Smoking is the only identified risk factor. Incidence patterns implicate reduced access to healthcare and many registered cases have only a clinical diagnosis. Favourable prognosis subtypes with specific clinical and histopathological criteria must be recognised and treated on the basis of the presumed primary site. Emerging data reveal high rates of emergency department admission, hospitalisations and psychological distress, and low rates of specialist consultations for patients with CUP. General practitioners (GPs) have a key role in earlier identification, integrated care and preventing patients with CUP from falling through the cracks.