Short summary

Cancer of Unknown Primary (CUP) is a rare, aggressive cancer with metastasis but no detectable primary tumor despite extensive testing. It has a poor prognosis and limited treatment options, with lengthy diagnostics worsening outcomes. Treatment is centralized at three Danish cancer centers, while diagnostics occur nationwide. Improved outcomes require better diagnostics, enhanced research, and international collaboration to develop evidence-based treatments and reduce unnecessary procedures.

Rationale

Cancer of Unknown Primary (CUP) is a rare and aggressive cancer, diagnosed in 3-5% of cancer patients. It is defined as a biopsy-confirmed cancer that has spread, but the primary tumor cannot be identified despite extensive testing. CUP patients often present with widespread and atypical metastases, and the disease generally has a poor prognosis with short survival. If the primary tumor remains unidentified, patients are referred to specialized cancer centers for treatment. In Denmark, medical oncology treatment for CUP is provided at three cancer centers: Rigshospitalet (RH), Aarhus University Hospital (AUH), and Odense University Hospital (OUH). The diagnostic process, however, occurs across various surgical and medical departments. The inability to identify the primary tumor results in prolonged diagnostic timelines, prognostic uncertainty, and limited treatment options. Despite advances in diagnostic methods, the average time for diagnosis and the number of tests have remained consistent over the past 15 years, causing patients to undergo unnecessary, time-consuming, and burdensome tests. This contributes to a poor prognosis as patients' conditions worsen during the diagnostic process, preventing timely treatment. Current treatment for CUP is based on small Phase II studies, with combination chemotherapy (platinum and taxane) showing some survival benefits. However, no standard treatment exists, and additional lines of treatment are offered only to patients in good general health. Only about 20% of CUP patients survive for one year, and the median survival is 3 months. Recent advances in personalized medicine have led to genomic testing for patients with incurable cancer, offering the possibility of targeted treatments based on DNA and RNA changes. CUP patients are increasingly being offered genomic testing, but there is limited knowledge about its impact on their outcomes. More research and collaboration are needed to improve treatment and survival for CUP patients.

Description of the cohort

Patients treated for CUP at the oncology departments of RH, OUH, or AUH can be included in the database. This also applies to patients assessed or evaluated but discharged without treatment. Data for the database is prospectively collected from the medical records of living patients. Additionally, deceased patients from the period 1/1/2018 to 31/12/2023 are included.

Data and biological material

Data from medical charts

Collaborating researchers and departments

Department of Oncology, Rigshospitalet

• MD phd Katharina Anne Perell
• MD phd Gedske Daugaard

Department of Oncology, Aarhus University hospital

• MD, phd. Louise Mahncke Guldbrandt