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 ⁶⁸ Ga-PSMA-11 (59% of the patients) or ¹⁸ F-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_max¹⁸ F-PSMA: median 5.1 vs 9.6, P = 0.002; SUV_max⁶⁸ Ga-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_max¹⁸ F-PSMA: 7.9 vs 12.3, P = 0.04; SUV_max⁶⁸ Ga-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 ⁶⁸ Ga-PSMA-11 (per doubling: odds ratio [OR] 1.96, 95% confidence interval [CI] 1.27-3.01)) and ¹⁸ F-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.