The additional value of 68Ga-PSMA PET/CT SUVmax in predicting ISUP GG ≥ 2 and ISUP GG ≥ 3 prostate cancer in biopsy.

BACKGROUND: Prebiopsy magnetic resonance imaging (MRI) increases the detection rate of clinically significant prostate cancer (csPCa). Prostate-specific membrane antigen-positron emission tomography/computed tomography (PSMA PET/CT) maximum standardized uptake value (SUVmax) of the prostate may offer additional value in predicting the likelihood of csPCa in biopsy. METHODS: A single-center cohort study involving patients with biopsy-proven PCa who underwent both MRI and PSMA PET/CT between 2020 and 2021. Logistic regression models were developed for International Society of Urological Pathology (ISUP) Grade Group (GG) ≥ 2 and GG ≥ 3 using noninvasive prebiopsy parameters: age, (log-)prostate-specific antigen (PSA) density, PI-RADS 5 lesion presence, extraprostatic extension (EPE) on MRI, and SUVmax of the prostate. Models with and without SUVmax were compared using Likelihood ratio tests and area under the curve (AUC). DeLong's test was used to compare the AUCs. RESULTS: The study included 386 patients, with 262 (68%) having ISUP GG ≥ 2 and 180 (47%) having ISUP GG ≥ 3. Including SUVmax significantly improved both models' goodness of fit (p < 0.001). The GG ≥ 2 model had a higher AUC with SUVmax 89.16% (95% confidence interval [CI]: 86.06%-92.26%) than without 87.34% (95% CI: 83.93%-90.76%) (p = 0.026). Similarly, the GG ≥ 3 model had a higher AUC with SUVmax 82.51% (95% CI: 78.41%-86.6%) than without 79.33% (95% CI: 74.84%-83.83%) (p = 0.003). The SUVmax inclusion improved the GG ≥ 3 model's calibration at higher probabilities. CONCLUSION: SUVmax of the prostate on PSMA PET/CT potentially improves diagnostic accuracy in predicting the likelihood of csPCa in prostate biopsy.

The association of quantitative PSMA PET parameters with pathologic ISUP grade: an international multicenter analysis.

PURPOSE: To assess if PSMA PET quantitative parameters are associated with pathologic ISUP grade group (GG) and upgrading/downgrading. METHODS: PCa patients undergoing radical prostatectomy with or without pelvic lymph node dissection staged with preoperative PSMA PET at seven referral centres worldwide were evaluated. PSMA PET parameters which included SUVmax, PSMAvolume, and total PSMA accumulation (PSMAtotal) were collected. Multivariable logistic regression evaluated the association between PSMA PET quantified parameters and surgical ISUP GG. Decision-tree analysis was performed to identify discriminative thresholds for all three parameters related to the five ISUP GGs The ROC-derived AUC was used to determine whether the inclusion of PSMA quantified parameters improved the ability of multivariable models to predict ISUP GG ≥ 4. RESULTS: A total of 605 patients were included. Overall, 2%, 37%, 37%, 10% and 13% patients had pathologic ISUP GG1, 2, 3, 4, and 5, respectively. At multivariable analyses, all three parameters SUVmax, PSMAvolume and PSMAtotal were associated with GG ≥ 4 at surgical pathology after accounting for PSA and clinical T stage based on DRE, hospital and radioligand (all p < 0.05). Addition of all three parameters significantly improved the discrimination of clinical models in predicting GG ≥ 4 from 68% (95%CI 63 - 74) to 74% (95%CI 69 - 79) for SUVmax, 72% (95%CI 67 - 76) for PSMAvolume, 74% (70 - 79) for PSMAtotal and 75% (95%CI 71 - 80) when all parameters were included (all p < 0.05). Decision-tree analysis resulted in thresholds that discriminate between GG (SUVmax 0-6.5, 6.5-15, 15-28, > 28, PSMAvol 0-2, 2-9, 9-20 and > 20 and PSMAtotal 0-12, 12-98 and > 98). PSMAvolume was significantly associated with GG upgrading (OR 1.03 95%CI 1.01 - 1.05). In patients with biopsy GG1-3, PSMAvolume ≥ 2 was significantly associated with higher odds for upgrading to ISUP GG ≥ 4, compared to PSMAvolume < 2 (OR 6.36, 95%CI 1.47 - 27.6). CONCLUSION: Quantitative PSMA PET parameters are associated with surgical ISUP GG and upgrading. We propose clinically relevant thresholds of these parameters which can improve in PCa risk stratification in daily clinical practice.

Immunohistochemical and histopathological validation of 18 F-PSMA-1007 PET/CT for intraprostatic cancerous lesions.

INTRODUCTION: Prostate-specific membrane antigen (PSMA) is overexpressed in prostate cancer (PCa). In this study, we aim to immunohistochemically and histopathological validate the fluorine-18 (18 F)-PSMA-1007 positron emission tomography/computed tomography (PET/CT) for intraprostatic PCa lesions. METHODS: Between February 2019 and October 2020, patients with biopsy-proven, treatment-naïve intermediate-to-high-risk PCa undergoing an 18 F-PSMA-1007 PET/CT before robot-assisted radical prostatectomy (RARP) were prospectively enrolled. For all PCa lesions found on whole-mount histopathology, location, size, International Society of Urological Pathology (ISUP) grade group (GG), and immune reactive score (IRS) were assessed after PSMA staining. ISUP GG ≥ 3 PCa was defined as clinically significant (cs) PCa. All lesions were matched on PSMA PET/CT and the maximum standardized uptake value (SUVmax) was measured. RESULTS: A total of 125 lesions were analyzed in the 80 RARP specimens, of which 49 (40%) were csPCa and 76 (60%) non-csPCa. Linear multivariable regressions showed that an increase in SUVmax significantly correlated with a higher ISUP GG (p values between 0.021 and 0.001) and a higher IRS (p = 0.017). Logistic multivariable regression showed that csPCa significantly correlated with a higher SUVmax (odds ratio, OR: 1.17 [95% confidence interval, CI: 1.04-1.21, p = 0.005]), an increase in tumor length (OR: 1.05 [95% CI 1.01-1.10, p = 0.020]) and a higher IRS (OR; 1.24 [95% CI 1.07-1.47, p = 0.006]). A SUVmax threshold of 4 would have resulted in one (2%) missed lesion with csPCa. CONCLUSION: This prospective study revealed that 18 F-PSMA-1007 PET/CT SUVmax is correlated with the ISUP GG and IRS, and thereby could be a tool to characterize intraprostatic PCa lesions.

A side-specific nomogram for extraprostatic extension may reduce the positive surgical margin rate in radical prostatectomy.

PURPOSE: Nomograms predicting side-specific extraprostatic extension (EPE) may be applied to reduce positive surgical margin (PSM) rates in patients planned for radical prostatectomy (RP). This study evaluates the impact of implementing an externally validated nomogram for side-specific EPE on PSM rate and degree of nerve-sparing. METHODS: In patients planned for RP, the side-specific nomogram predictions (based on MRI, ISUP grade group, and PSA density), with an advised threshold of 20% for safe nerve-sparing, were presented preoperatively to the urological surgeon. The surgeon completed a survey before RP about the planning with respect to side-specific nerve-sparing and change of management due to the result of the nomogram. PSM rates and degree of nerve-sparing were compared to a retrospective control group treated in the months prior to the introduction of the nomogram. RESULTS: A total of 100 patients were included, 50 patients in both groups representing 200 prostate lobes. Of the patients, 37% had histologically confirmed EPE, and 40% a PSM. In 12% of the 100 lobes planned after nomogram presentation, a change in management due to the nomogram was reported. A per-prostate lobe analysis of all the lobes showed comparable rates of full nerve-sparing (45% vs. 30%; p = 0.083) and lower rates of PSM on the lobes with histological EPE (45% vs. 85%; p < 0.05) in the intervention (nomogram) group versus the control group. CONCLUSION: Implementing a predictive nomogram for side-specific EPE in the surgical planning for nerve-sparing leads to lower rates PSM on the side of the histological EPE without compromising nerve-sparing.

Gallium-68 Prostate-specific Membrane Antigen Positron Emission Tomography/Computed Tomography in Active Surveillance for Prostate Cancer Trial (PASPoRT).

BACKGROUND: The use of clinical parameters, including prebiopsy magnetic resonance imaging (MRI), to decide between active surveillance (AS) and active therapy for prostate cancer (PCa) leads to imperfect selection. Additional prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) imaging may improve risk stratification. OBJECTIVE: To study risk stratification and patient selection for AS with the addition of PSMA PET/CT to standard practice. DESIGN, SETTING, AND PARTICIPANTS: A single-centre prospective cohort study (NL69880.100.19) enrolled patients recently diagnosed with PCa who started AS. At diagnosis, all participants had undergone prebiopsy MRI and targeted biopsy for visualised lesions. Patients underwent an additional [68Ga]-PSMA PET/CT and targeted biopsy of all PSMA lesions with a maximum standardised uptake value (SUVmax) of ≥4 not covered by previous biopsies. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary outcome was the number needed to scan (NNS) to detect one patient with upgrading. The study was powered to detect an NNS of 10. Regarding secondary outcomes, univariate logistic regressions analyses were performed on all patients and on the patients who received additional PSMA targeted biopsies on the likelihood of upgrading. RESULTS AND LIMITATIONS: A total of 141 patients were included. Additional PSMA targeted biopsies were performed in 45 (32%) patients. In 13 (9%) patients, upgrading was detected: nine grade group (GG) 2, two GG 3, one GG 4, and one GG 5. The NNS was 11 (95% confidence interval 6-18). Of all participants, PSMA PET/CT and targeted biopsies yielded upgrading most frequently in patients with negative MRI (Prostate Imaging Reporting and Data System [PI-RADS] 1-2). Of patients who received additional PSMA targeted biopsies, upgrading was most frequently found in those with higher prostate-specific antigen density and negative MRI. Limitations included the lack of comparison with standard repeat biopsy, no central review of MRI, and possibility of biopsy sampling error. CONCLUSIONS: PSMA PET/CT can further improve PCa risk stratification and selection for AS patients diagnosed after MRI and targeted biopsies. PATIENT SUMMARY: Prostate-specific membrane antigen positron emission tomography/computed tomography and additional targeted prostate biopsies can identify more aggressive prostate cancer cases previously missed in patients recently started with expectant management for favourable-risk prostate cancer.

Oncologic Outcomes of Incidental Versus Biopsy-diagnosed Grade Group 1 Prostate Cancer: A Multi-institutional Study.

Background and objective: Patients diagnosed with grade group (GG) 1 prostate cancer (PCa) following treatment for benign disease ("incidental" PCa) are typically managed with active surveillance (AS). It is not known how their outcomes compare with those observed in patients diagnosed with GG1 on biopsy. We aimed at determining whether long-term oncologic outcomes of AS for patients with GG1 PCa differ according to the type of diagnosis: incidental versus biopsy detected. Methods: A retrospective, multi-institutional analysis of PCa patients with GG1 on AS at eight institutions was conducted. Competing risk analyses estimated the incidence of metastases, PCa mortality, and conversion to treatment. As a secondary analysis, we estimated the risk of GG ≥2 on the first follow-up biopsy according to the type of initial diagnosis. Key findings and limitations: A total of 213 versus 1900 patients with incidental versus biopsy-diagnosed GG1 were identified. Patients with incidental cancers were followed with repeated biopsies and multiparametric magnetic resonance imaging less frequently than those diagnosed on biopsy. The 10-yr incidence of treatment was 22% for incidental cancers versus 53% for biopsy (subdistribution hazard ratio [sHR] 0.34, 95% confidence interval [CI] 0.26-0.46, p < 0.001). Distant metastases developed in one patient with incidental cancer versus 17 diagnosed on biopsy and were diagnosed with molecular imaging in 13 (72%) patients. The 10-yr incidence of metastases was 0.8% for patients with incidental PCa and 2% for those diagnosed on biopsy (sHR 0.35, 95% CI 0.05-2.54, p = 0.3). The risk of GG ≥2 on the first follow-up biopsy was low if the initial diagnosis was incidental (7% vs 22%, p < 0.001). Conclusions and clinical implications: Patients with GG1 incidental PCa should be evaluated further to exclude aggressive disease, preferably with a biopsy. If no cancer is found on biopsy, then they should receive the same follow-up of a patient with a negative biopsy. Further research should confirm whether imaging and biopsies can be avoided if postoperative prostate-specific antigen is low (<1-2 ng/ml). Patient summary: We compared the outcomes of patients with low-grade prostate cancer on active surveillance according to the type of their initial diagnosis. Patients who have low-grade cancer diagnosed on a procedure to relieve urinary symptoms (incidental prostate cancer) are followed less intensively and undergo curative-intended treatment less frequently. We also found that patients with incidental prostate cancer are more likely to have no cancer on their first follow-up biopsy than patients who have low-grade cancer initially diagnosed on a biopsy. These patients have a more favorable prognosis than their biopsy-detected counterparts and should be managed the same way as patients with negative biopsies if they undergo a subsequent biopsy that shows no cancer.

Clinically Significant Prostate Cancer Diagnosis Without Histological Proof: A Possibility in the Prostate-specific Membrane Antigen Era?

Magnetic resonance imaging (MRI) has resulted in a reduction in the number of patients indicated for prostate biopsy. Prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) has recently shown additional value in detecting clinically significant prostate cancer (csPCa). Combining these imaging modalities allows such specific prediction of the presence of csPCa that the need for histological confirmation may be obsolete. We retrospectively analyzed PSMA PET/CT scans performed in the primary staging of PCa in the past 2 yr in our center (n = 451). All 74 patients with a PSMA ligand maximum standardized uptake value (SUVmax) of ≥16 had csPCa (grade group ≥2). Of the 185 patients with a combination of a Prostate Imaging-Reporting and Data System score ≥4 and SUVmax ≥8, 98% had csPCa. A nomogram combining predictive factors should be developed to identify patients in whom biopsy could theoretically be avoided. Nevertheless, biopsy will remain indispensable in patients with indefinite risk of csPCa and can provide important additional information. Patient summary: Using patient data from our center, we found that addition of a special type of scan based on prostate-specific membrane antigen could help in the diagnosis of clinically significant prostate cancer without the need for prostate biopsy. Direct therapy without biopsy confirmation of cancer might be possible for a highly select group of patients.

Superfast Magnetic Resonance Imaging-based Diagnostic Pathway for Prostate Cancer.

We describe a <36-h superfast diagnostic pathway for men at risk of prostate cancer (PCa) that was initiated in our centre in March 2022. Patients are scheduled to undergo a repeat prostate-specific antigen blood test, magnetic resonance imaging, a urology consultation, and, if indicated, prostate biopsies in a single morning. The histopathology report is available the next day, after which the biopsy results and treatment options are discussed via a telephone consultation. The project has included 122 patients so far. With a reduction to only one hospital visit per patient and just five appointments (4%) cancelled so far, this timely pathway seems to be efficient from a patient perspective. In addition, reducing the waiting time until histopathology diagnosis could decrease the anxiety and depression that patients may experience during the diagnostic workup for PCa. Therefore, we believe that this fast-track diagnostic pathway could be incorporated in the future European standard of care, bringing PCa care in line with other malignancies such as breast cancer. Patient summary: We describe a superfast diagnostic pathway for men at risk of prostate cancer. So far, this strategy seems to be an efficient and appropriate way to shorten time to diagnosis and to reduce the number of hospital visits for patients.