Comparing the diagnostic accuracy of 68Ga-PSMA and 11C-Choline PET/CT scan according to PSA level: A large multi-institutional analysis with histological verification in patients treated with salvage lymph node dissection for recurrent prostate cancer

INTRODUCTION AND OBJECTIVES:Despite high specificity, PET/CT scan is limited by relatively low sensitivity at a lesion-based analysis in the context of recurrent prostate cancer (PCa). Moreover, underestimation of tumour burden may be related to the extent of tracer uptake. We hypothesized that under-estimation of tumour burden varies significantly according to PET/CT tracer by PSA level at salvage lymph node dissection (SLND)METHODS:We included 458 patients who received extended SLND at eleven tertiary referral centres. All patients were diagnosed with PET/CT scan using either 11C-choline (n=293; 64%) or 68Ga-PSMA (n=165; 36%). The study outcome was under-estimation of tumour burden calculated: number of positive nodes at SLND - number of positive spots at PET/CT. Multivariable linear regression analysis (MVA) tested the association between under-estimation of tumour burden and PET/CT tracer (11C-choline vs. 68Ga-PSMA). We tested an interaction with PSA and PET/CT tracer for the hypothesis that under-est...