SUV<sub>max</sub> Above 20 in <sup>18</sup>F-FDG PET/CT at Initial Diagnostic Workup Associates with Favorable Survival in Patients with Cancer of Unknown Primary.

Zaun, Gregor; Weber, Manuel; Metzenmacher, Martin; Wiesweg, Marcel; Hilser, Thomas; Zaun, Yasmin; Liffers, Sven; Pogorzelski, Michael et al. · J Nucl Med · 2023

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Abstract

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. <b>Methods:</b> In CUP patients treated at the West German Cancer Center Essen, the prognostic value of <sup>18</sup>F-FDG PET/CT at the initial diagnostic workup was analyzed by comparing overall survival (OS) in patients who underwent <sup>18</sup>F-FDG PET/CT with those who did not. <b>Results:</b> Of 154 patients with a CUP diagnosis, 76 underwent <sup>18</sup>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<sub>max</sub> 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; <i>P</i> = 0.009). <b>Conclusion:</b> Our retrospective work shows that an SUV<sub>max</sub> above 20 on <sup>18</sup>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.

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