Epidemiology and Management of Neuroendocrine Neoplasms of Unknown Primary in Switzerland
Lena Kathrin Rhonheimer, Julia Beck, Alexander R. Siebenhüner, Damian Wild, Emanuel R. Christ, Julie RefardtAbstract
Background
Neuroendocrine neoplasms (NEN) are mainly located in the gastrointestinal tract or the lungs. In up to 14%, the primary tumor remains unidentified, classified as cancer of unknown primary (CUP). Due to their rarity and heterogeneity, CUPs are poorly studied.
Methods
Retrospective data analyses with data provided by the SwissNET registry from 2008-2022 including patients diagnosed with CUP or metastasised NEN with known primary (mNEN). Main objective was to assess the demographics, tumor characteristics and the diagnosis and treatment of CUPs in comparison to mNEN. Secondary objective was to evaluate overall survival of CUPs in general and compared to mNEN using propensity score matching.
Results
207 CUP and 437 mNEN patients were included. Prevalence was slightly higher in men (54.6% and 57.9%, respectively). Median (IQR) age at diagnosis was higher for patients with a CUP (67.7 years (59.0, 77.2)) compared to mNEN (62.9 years (53.5, 71.5), p < .001). Grading in CUP patients was higher compared to mNEN with G1 (20.8% vs. 38.0%), G2 (30.4% vs. 43.5%) and G3 classified tumours ((32.9% vs. 9.6%), p < .001). Main CUP treatment involved somatostatin analogues (42%), followed by chemotherapy (32%) and PRRT (30%). Median survival time was significantly shorter for CUP patients compared to mNEN patients (23.3 months (95-CI [15.5, 31.1]) vs 151.5 months (95-CI [122.8, 180.1], p < .001)). This difference persisted after propensity score matching (p = .007).
Conclusion
Overall survival time of patients with CUPs was shorter compared to mNEN, possibly due to the higher-grade tumors at diagnosis.