- Background: Cancer of Unknown Primary (CUP) is a form of malignancy for which a primary site cannot be identified despite extensive investigations. The Royal Derby Hospital (RDH) have recently adopted UK Oncology Nursing Society (UKONS) guidelines which aim to promote early involvement of the CUP service, reduce delays in diagnosis and treatment, and prevent unnecessary investigations for suspected CUP patients.Method: A database for patients referred to the CUP service at RDH was compiled by CUP specialist nurses during the period May 2015-May 2016.Results: Referrals to the CUP service were decreased (25%) compared with the previous year but patients diagnosed with CUP had a reduced average life expectancy (17%). The number of MDT discussions per patient was reduced (18%) and time to diagnosis decreased by 29% compared with 2014-15. Only 24% of patients undergoing a biopsy received active treatment.Conclusion: Reduced referrals to the RDH CUP service and more efficient diagnoses do not translate to improved survival rates although this may be attributable to the inclusion of patients deceased prior to referral. Neither do invasive biopsies tend to alter management plans for patients. A restructuring of the national coding system for CUP would better serve patients if it were to differentiate between those who are unfit for investigations and true CUP patients. Finally, involving Haematology and Lung specialists in the CUP MDT may more efficiently identify those referred patients with site-specific cancers.