⁶⁸ Ga-Prostate-Specific Membrane Antigen Positron Emission Tomography Maximum Standardized Uptake Value as a Predictor of Gleason Pattern 4 and Pathological Upgrading in Intermediate-Risk Prostate Cancer

Abstract

Purpose:Accurate risk stratification remains a barrier for the safety of active surveillance in patients with intermediate-risk prostate cancer. [68Ga]Ga-PSMA-11 prostate-specific membrane antigen positron emission tomography/computerized tomography (68Ga-PSMA PET/CT) and the maximum standardized uptake value (SUVmax) may improve risk stratification within this population.Materials and Methods:We reviewed men with International Society for Urological Pathology Grade Group (GG) 2–3 disease on transperineal template biopsy undergoing 68Ga-PSMA PET/CT from November 2015 to January 2021. Primary outcome was the presence of high percentage Gleason pattern 4 (GP4) disease per segment at surgery at 3 thresholds: >/<50% GP4, >/<20% GP4, and >/<10% GP4. SUVmax was compared by GP4, and multivariable logistic regression examined the relationship between SUVmax and GP4. Secondary outcome was association between SUVmax and pathological upgrading (GG 1/2 to GG ≥3 from biopsy to surgery).Results:Of 220 men who underwent biopsy, 135 men underwent surgery. SUVmax was higher in high GP4 groups: 5.51 (IQR 4.19–8.49) vs 3.31 (2.64–4.41) >/<50% GP4 (p <0.001); 4.77 (3.31–7.00) vs 3.13 (2.64–4.41) >/<20% GP4 (p <0.001); and 4.54 (6.10–3.13) vs 3.03 (2.45–3.70) >/<10% GP4 (p <0.001). SUVmax remained an independent predictor of >50% (OR=1.39 [95%CI 1.18–1.65], p <0.001) and >20% (OR=1.24 [1.04–1.47], p=0.015) GP4 disease per-segment, and of pathological upgrading (OR=1.22 [1.01–1.48], p=0.036). SUVmax threshold 4.5 predicted >20% GP4 with 58% specificity, 85% sensitivity, positive predictive value 75% and negative predictive value 72%. Threshold 5.4 predicted pathological upgrading with 91% specificity and negative predictive value 94%.Conclusions:SUVmax on 68Ga-PSMA PET/CT is associated with GP4. SUVmax may improve risk stratification for men with intermediate-risk prostate cancer.

Could 68Ga-PSMA PET/CT Evaluation Reduce the Number of Scheduled Prostate Biopsies in Men Enrolled in Active Surveillance Protocols?

“…The presence of focal uptake on PSMA-PET/CT, the standardised uptake value (SUVmax) and the maximal dimensions of PET-avid lesions have been correlated with the presence of csPCa [ 20 , 21 ]. There is a range of proposed cutoffs to detect csPCa from SUVmax 3.15 to up SUVmax 9.1 [ 22 , 23 ]; the concordance between preoperative PSMA PET/TC evaluation (SUVmax, dimension of the lesion), and definitive prostate specimen ranges from 81.2% (24) to 96% [ 24 , 25 , 26 , 27 , 28 ]. Moreover, PSMA PET/MRI seems to reduce the false positive rate of PET/CT (about 8% of cases) [ 26 ].…”

Grade and stage misclassification in intermediate unfavorable‐risk prostate cancer radiotherapy candidates

“…23,24 Since the ability of MRI to improve prediction of upgrading and/or upstaging is still under debate, other clinical tools, such as PSMA PET/CT scans or biomarkers (the prostate health index, urine PCA3, 4Kscore, TMPRSS2-ERG, and ConfirmMDX) may prove of value. 25,26 Moreover, despite novel findings, these tools still have to prove their efficacy and are not currently available in the clinical practice. 9 We demonstrated that upgrading affects a relatively small proportion of misclassified patients.…”

“…Furthermore, other studies reported an underestimation of MRI regarding the true size and extend of PCa tumor 23,24 . Since the ability of MRI to improve prediction of upgrading and/or upstaging is still under debate, other clinical tools, such as PSMA PET/CT scans or biomarkers (the prostate health index, urine PCA3, 4Kscore, TMPRSS2–ERG, and ConfirmMDX) may prove of value 25,26 . Moreover, despite novel findings, these tools still have to prove their efficacy and are not currently available in the clinical practice.…”

Modern paradigms for prostate cancer detection and management

“…Maximum standardised uptake value (SUVmax) is a measurement of tracer uptake in tissue for PET imaging. Greater SUVmax on PSMA PET/CT was associated with clinically significant prostate cancer (International Society for Urological Pathology [ISUP] grade group 3–5) on biopsy 30,31 . The combination of PI‐RADS score and PSMA PET/CT SUVmax provided higher sensitivity and negative predictive value than individually with the addition of PSMA PET/CT alongside mpMRI 30 .…”

“…Greater SUVmax on PSMA PET/CT was associated with clinically significant prostate cancer (International Society for Urological Pathology [ISUP] grade group 3-5) on biopsy. 30,31 The combination of PI-RADS score and PSMA PET/ CT SUVmax provided higher sensitivity and negative predictive value than individually with the addition of PSMA PET/CT alongside mpMRI. 30 The PRIMARY trial, a recent Australianled multicentre trial, evaluated the use of pelvic PSMA PET/CT in the diagnosis of intraprostatic malignancy in men with mpMRI PI-RADS 2-5.…”