Cancer of unknown primary (CUP) is a heterogeneous clinical syndrome with complicated and prolonged diagnostic pathway, representing 3-5% of all malignancies . UK National Institute for Health and Clinical Excellence (NICE), defines three types of CUP. The clinically diagnosed metastatic cancer without histopathological confirmation (malignancy of undefined primary, MUO); the cytologically or histologically confirmed metastatic malignancy following initial investigations (provisional CUP, pCUP); and, the histopathologically confirmed after appropriate specialised investigations (confirmed CUP, cCUP) .
This retrospective study reviewed the diagnostic pathway and management of patients presenting as CUP in Medway Hospital, Kent, UK, between April 2017 and March 2018. The purpose of the audit was to provide the framework of investigation and subsequent management of patients presenting with MUO. We aimed to improve delays on the diagnostic pathway and subsequent outcomes for both patients who should be treated radically and, those with a poor prognosis who may benefit from palliative care .
Seventy-three patients presented with MUO. Forty-six primary cancers (63%) were identified, following clinical, radiological and, pathological review, enabling prompt referrals to relevant specialist teams [Table 1, Graphic 1]. Histology was not obtained in 11 cases (15%), taken that the results would not influence patients’ management. Among the 16 CUP patients (22%), 11 were pCUP (15%), whereas 5 were diagnosed with cCUP (7%), respectively. Three out of the 5 patients with cCUP (60%) received treatment, while the remaining 2 (40%) were treated with palliative care. The overall survival of the cCUP patients was 159 days (ranged 48 to 303) [Table 2].
Even though, CUP has been recognized as a clinical entity, the incidence of the MUO, pCUP and cCUP subtypes, is still unknown. Differentiation of these subtypes would help clarify the public health burden of the disease. The therapeutic consideration should include treatment for patients presenting with treatable phenotypes and palliative care for those who do not.