Utility of 18F-FDG PET/CT in treatment strategies for patients with cancer of unknown primary

Abstract

Objective To evaluate the role of 18F-FDG PET/CT imaging in primary tumor detection and treatment formulation in patients with cancer of unknown primary (CUP). Methods Sixty-two patients with CUP were selected from a database consisting of 18,802 cases in the Jiangsu Cancer Hospital PET/CT centre from 18 May 2016 to 18 November 2022. Clinical data and changes in treatment strategies before and after PET/CT were collected. Results A total of 42 primary tumors (42/62, 67.7%) were identified by PET/CT examination. The tumor staging of patients before conventional PET/CT imaging (such as CT/MRI/US) and after PET/CT did not change in 28 patients (28/62, 45.2%), whereas for 35 patients (34/62, 54.8%) tumor staging changed. Forty-five patients (45/62, 72.6%) had not developed treatment plans before PET/CT examination, but treatment plans were clarified after PET/CT examination. Thirteen patients (13/62, 21.0%) underwent changes in treatments before and after PET/CT examination. Among the 20 patients (20/62, 32.3%) whose primary tumors were not detected, 16 patients (16/20, 80.0%) had no treatment plans before PET/CT and the treatment plans were defined after PET/CT, three patients (3/20, 15.0%) changed the treatment plans before and after PET/CT, and one patient (1/20, 5.0%) did not change the treatment plan. Conclusion 18F-FDG PET/CT plays an important role in the detection and staging of primary tumors in patients with CUP. PET/CT findings can not only help clinicians develop appropriate treatment plans for patients with CUP, but also serve as an effective approach to improve real-life treatment strategies for these patients.