SUV Above 20 in F-FDG PET/CT at Initial Diagnostic Workup Associates with Favorable Survival in Patients with Cancer of Unknown Primary.

Cancer of unknown primary (CUP) is a heterogeneous entity with a limited prognosis. Novel prognostic markers are needed for patient stratification in prospective clinical trials exploring innovative therapies. In CUP patients treated at the West German Cancer Center Essen, the prognostic value of F-FDG PET/CT at the initial diagnostic workup was analyzed by comparing overall survival (OS) in patients who underwent F-FDG PET/CT with those who did not. Of 154 patients with a CUP diagnosis, 76 underwent F-FDG PET/CT at the initial diagnostic workup. The median overall survival (OS) of the full analysis set was 20.0 mo. Within the PET/CT subgroup, an SUV above 20 was associated with significantly superior OS (median OS, not reached vs. 32.0 mo; hazard ratio, 0.261; 95% CI, 0.095-0.713; = 0.009). Our retrospective work shows that an SUV above 20 on F-FDG PET/CT at the initial diagnostic workup is a favorable prognostic factor in patients with CUP. This finding deserves further prospective studies for validation.