Background

Patients presenting with clinical or radiological evidence suggesting metastatic disease without an obvious primary site are said to have malignancy of undefined primary origin (MUO). Where clinically appropriate, comprehensive investigations, including tissue biopsy, may lead to identification of a primary site, a non-cancer diagnosis or a diagnosis of cancer of unknown primary (CUP). The National Institute for Clinical Excellence recommends that oncology centres establish a “CUP Team” to provide advice and support to non-cancer teams on appropriate investigations and management of patients presenting with MUO/CUP. We sought to define outcomes of patients referred to a regional CUP team. 

Method

Prospective data collection was undertaken of all patients referred to the Edinburgh Cancer Centre CUP team between 2010-2019. Patient demographics, clinical and pathological data were recorded. Survival, defined as the date of radiological diagnosis of MUO until death was calculated.

Results

Data were available for 1000 patients. Median survival was 4.3 months. 24% of patients were unsuitable for comprehensive investigation (final diagnosis of MUO) and their median survival was only 1.5 months. 7% of patients received a non-cancer diagnosis. A primary site was identified in 38%. Only 25% of patients with a final diagnosis of CUP were fit enough to attend the CUP outpatient clinic and their median survival was 4.2 months. Half of these patients had immunohistochemical features consistent with hepatobiliary/pancreatic cancer and 26% belonged to a recognised CUP clinicopathological favourable prognosis group. Only 34% of patients with CUP received systemic anti-cancer therapy (SACT), with median survival 10.9 months.

Conclusion

Patients with MUO/CUP often have very poor outcomes. Early referral to a CUP team may ensure suitable patients are considered early for SACT and assist non-cancer clinical teams to avoid comprehensive investigations for those in whom anti-cancer therapy is not clinically appropriate.

Impact statement

Patients with MUO/CUP often have very poor outcomes, and a specialist CUP team can ensure early decision making regarding investigations and treatment for this patient group.