Standardised uptake values as determined on prostate-specific membrane antigen positron emission tomography/computed tomography is associated with oncological outcomes in patients with prostate cancer

Objectives: To investigate the association between intraprostatic, intratumoral maximum standardised uptake values (SUV _max) on prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) in patients with prostate cancer (PCa) prior to robot-assisted radical prostatectomy (RARP) and pathology outcomes, including pathological International Society of Urological Pathology score (pISUP) and lymph node (LN) status (pN0/pN1). Patients and Methods: A bi-centric, secondary analysis of two previous, prospective cohort studies was performed in 318 patients with biopsy confirmed PCa and who were scheduled for RARP. Before surgery, patients received a PSMA PET/CT with either ⁶⁸Ga-PSMA-11 (59% of the patients) or ¹⁸F-PSMA (DCFPyL; 41%) as radiotracer. PET/CT images were analysed both visually and semi-quantitatively by measuring the SUV _max of the most intense suspect lesion in the prostate. The association between the SUV _max of the primary tumour and pre- and postoperative variables was analysed. Results: The SUV _max was associated with clinical and biopsy preoperative variables, as well as with pISUP score and pathological tumour stage. Patients with a pISUP of ≤2 showed significantly lower SUV _max compared to patients with a pISUP of >2 for both tracers (SUV _max ¹⁸F-PSMA: median 5.1 vs 9.6, P = 0.002; SUV _max ⁶⁸Ga-PSMA-11: 6.6 vs 8.6, P = 0.003). Moreover, patients with pN1 had significantly higher median SUV _max than those with pN0/pNx for both tracers (SUV _max ¹⁸F-PSMA: 7.9 vs 12.3, P = 0.04; SUV _max ⁶⁸Ga-PSMA-11: 7.6 vs 12.0, P < 0.001). On multivariable logistic regression analysis, the intraprostatic SUV _max was an independent predictor of pN1 for both ⁶⁸Ga-PSMA-11 (per doubling: odds ratio [OR] 1.96, 95% confidence interval [CI] 1.27–3.01)) and ¹⁸F-PSMA (per doubling: OR 1.79, 95% CI 1.06–3.03). Conclusion: Intraprostatic, intratumoral PSMA intensity on PET/CT, as semi-quantitatively expressed by SUV _max, may be a valuable innovative biomarker in patients with localised PCa, as it is highly associated with known conventional prognostic factors, such as pISUP and LN status.