Introduction: Carcinoma of unknown primary (CUP) represents a diagnostic and therapeutic challenge.  Both clinicians and patients often find the diagnosis frustrating.  Inability to locate the primary site of a cancer can be viewed as a diagnostic failure. 

Methods and Objectives: We conducted a national survey of members of the Medical Oncology Group of Australia to evaluate their understanding of CUP, assess recognition of the diagnosis, investigation procedures, and treatment protocols.

Results:  86 oncologists completed the survey, with 80 stating they are directly involved in the assessment of patients with CUP.  99% of those surveyed stated they were prepared to make a final diagnosis of CUP if after appropriate diagnostic tests the primary location of the cancer remained unclear.  27% stated that they would prefer to provide a best guess of the primary location of the cancer rather than diagnose CUP as a specific diagnostic entity, while a further 33% said that they would sometimes do this.  83% of respondents stated that they would provide a possible primary location of the cancer, and define the cancer as such in an effort to obtain PBS funding of a medical therapy.  62% stated they did not have a specific treatment protocol designed for patients with CUP.  The majority of clinicians used serum tumour markers and CT scan imaging in the initial diagnosis of CUP, whilst 43% indicated they would use a PET scan in at least 50% of suspected cases of CUP.  64% stated that they would arrange mammography in more than 90% of cases of female patients with suspected CUP.  The majority of clinicians do not apply a specific classification system when diagnosing CUP. 

Conclusions: The approach to diagnosis, investigation, classification and management of CUP in Australia is variable.  Many clinicians preferred to best guess the primary location and treat accordingly.  PBS restrictions appear to encourage the practice of ‘best guessing’ the primary and assigning a diagnosis other than CUP.