Value of 68Ga-PSMA HBED-CC PET for the Assessment of Lymph Node Metastases in Prostate Cancer Patients with Biochemical Recurrence: Comparison with Histopathology After Salvage Lymphadenectomy

New Prostate Cancer Targets for Diagnosis, Imaging, and Therapy: Focus on Prostate-Specific Membrane Antigen

The rising incidence rate of the cancer in the prostate gland has increased the demand for improved diagnostic, imaging, and therapeutic approaches. Prostate-specific membrane antigen (PSMA), with folate hydrolase and carboxypeptidase and, internalization activities, is highly expressed in the epithelial cells of the prostate gland and is strongly upregulated in prostatic adenocarcinoma, with elevated expression correlating with, metastasis, progression, and androgen independence. Recently, PSMA has been an active target of investigation by several approaches, including the successful utilization of small molecule inhibitors, RNA aptamer conjugates, PSMA-based immunotherapy, and PSMA-targeted prodrug therapy. Future investigations of PSMA in prostate cancer (PCa) should focus in particular on its intracellular activities and functions. The objective of this contribution is to review the current role of PSMA as a marker for PCa diagnosis, imaging, and therapy.

Metaanalysis of 68Ga-PSMA-11 PET Accuracy for the Detection of Prostate Cancer Validated by Histopathology

⁶⁸Ga-PSMA-11 PET is used to stage patients with prostate cancer. We performed an updated metaanalysis that separates imaging at the time of diagnosis and at the time of biochemical recurrence and focuses on pathology correlation in both populations. Methods: We searched the MEDLINE and EMBASE databases using the PRISMA statement. Quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool 2. In total, 1,811 studies were screened, 58 were analyzed, 41 were included for qualitative synthesis, and 29 were included for quantitative analysis. A random-effect model and a hierarchical summary receiver-operating-characteristic model were used to summarize the sensitivity, specificity, positive predictive value (PPV), negative predictive value, and accuracy for pelvic lymph nodes in initial staging compared with pathology at prostatectomy and the PPV for lesions with pathologic correlation in those with biochemical recurrence. We also summarized the detection rate of ⁶⁸Ga-PSMA-11 in those with biochemical recurrence stratified by prostate-specific antigen (PSA) at the time of imaging. Results: The metaanalysis of ⁶⁸Ga-PSMA-11 at initial staging demonstrated a sensitivity and specificity of 0.74 (95% confidence interval [95% CI], 0.51-0.89) and 0.96 (95% CI, 0.85-0.99), respectively, using nodal pathology at prostatectomy as a gold standard. At biochemical recurrence, the PPV was 0.99 (95% CI, 0.96-1.00). The detection rate was 0.63 (95% CI, 0.55-0.70), with a PSA of less than 2.0 and 0.94 (95% CI, 0.91-0.96) with a PSA of more than 2.0. Conclusion: ⁶⁸Ga-PSMA-11 performed well for the localization of metastatic prostate cancer at initial staging and at the time of biochemical recurrence.

Efficacy of early imaging with 68Ga-PSMA-I&T in the discrimination of pelvic lesions in prostate cancer patients

OBJECTIVE

⁶⁸Ga-PSMA-uptake shows accumulation in the malignant lesions of prostate cancer patients as early as 5min p.i. Studies indicate the value of adding an early image of the pelvis to the imaging protocol of ⁶⁸Ga-PSMA-11 PET/CT scan showed contradictory results. In this study we planned to assess the significance of an additional early imaging in ⁶⁸Ga-PSMA-I&T PET/CT imaging in prostate cancer patients.

MATERIALS AND METHODS

A total of 35 prostate cancer patients referred to ⁶⁸Ga-PSMA-I&T PET/CT imaging for restaging of the disease due to suspicion of relapse after definitive therapy were enrolled. First an early static pelvic image was obtained at a maximum of 300s following injection of the radiotracer. Sixty minutes postinjection a whole-body PET/CT scan was conducted with an emission time of 3min per bed position. The lesions which were categorized as local recurrence, bone lesion and lymph node metástasis in the early images, were compared with the late images in terms of number of lesions detected and SUVmax values.

RESULTS

⁶⁸Ga-PSMA-I&T PET/CT was positive in 23 of 35 patients (65.7%). A pathological uptake was observed in the prostatic bed site, in the pelvic lymph nodes, and in the bones in 17 patients (48.5%), 12 patients (34.2%), and 13 patients (37.1%), respectively. In one patient, focal pathological increased uptake in the prostatic bed with a SUVmax value of 5.8 was detected but this lesion disappeared in the late images. The average SUVmax values of the lesions in the prostatic bed were 13.7±12.1 versus 26.3±23.8 in the 5min and 60min studies respectively (p<0.001). In one patient, the pathological uptake in the lymph node in the early study cleared in the late study, whereas in another accumulation of activity was detected in a pelvic lymph node in the late study, while there was no lymph node detected in the early study. The average SUVmax values of the lymph nodes were 12.1±8.8 versus 26.3±22.6 in the 5min and 60min studies respectively (p<0.001). The average SUVmax values of the bone lesions were 11.4±6.9 versus 15±10.7 in the 5min and 60min studies respectively.

CONCLUSION

Our study is the first in the literature to evaluate the impact of adding an early static pelvic image to the ⁶⁸Ga-PSMA-I&T scan, in the detection rate of the lesions. Although there was no marked discordance between the 2sets of images, the addition of an early image to the imaging protocol of ⁶⁸Ga-PSMA-I&T scan would increase the efficacy of detection of malignant lesions in the pelvis, which might show rapid clearance and has the risk of being masked by the urinary system activity.

North American population-based validation of the National Comprehensive Cancer Network Practice Guideline Recommendations for locoregional lymph node and bone imaging in prostate cancer patients

BACKGROUND

The National Comprehensive Cancer Network (NCCN) guidelines provide recommendations for staging of prostate cancer patients in the objective regarding presence of locoregional lymph node metastases (LNM) and bone metastases. We tested the performance characteristics of these recommendations in a community setting.

METHODS

Within the Surveillance, Epidemiology, and End Results database (2004-2014), we identified patients with available Gleason, clinical stage and prostatic specific antigen. Performance characteristics endpoints consisted of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NVP), overall accuracy and the number needed to image (NNI).

RESULTS

Totally, 191,308 patients were assessable for the validation of the LNM staging recommendations. Sensitivity ranged from 80.6 to 86.3%, specificity from 74.7 to 79.3%, PPV from 7.8 to 8.0%, overall accuracy from 75.0 to 79.3% and NPV was 99.5%. The respective NNI values were 12.5 and 12.8. 197,408 patients were assessable for the validation of bone scan recommendations. These recommendations resulted in 90.8% sensitivity, 76.3% specificity, PPV of 5.7%, NPV of 99.8% and overall accuracy of 76.5%. The NNI was 17.5.

CONCLUSION

The NCCN recommendations for locoregional LNM miss few patients with clinical LNM (0.3-0.4%) and provide a virtually perfect NPV of 99.5%. Also, the recommendations for bone scan miss a marginal number of patients with established bone metastases (0.14%) and yield a virtually perfect NPV of 99.8%.

Prostate-specific membrane antigen positron emission tomography in the management of recurrent prostate cancer

INTRODUCTION

There is an unmet clinical need for early, accurate imaging of recurrent prostate cancer to improve patient outcomes. Staging, by conventional bone scintigraphy and CT have become outdated. 68Ga-PSMA PET/CT imaging in this setting has developed rapidly, with widespread International adoption in line with evidence-based guidelines in this group of patients.

SOURCES OF DATA

A PubMed search of English language articles was performed using following keywords: PSMA, PET/CT, biochemical recurrence, prostate cancer. The search revealed 85 articles, of which 75 were original; 70 of these involved use of the most widely available type of PSMA tracer (HBED). The review also relied on the clinical experience of reporting over 1000 PSMA PET/CT studies at a major tertiary referral centre for uro-oncology, with the majority of cases having been performed in the biochemical recurrence setting from 2015 to 2018.

AREAS OF AGREEMENT

68Ga-PSMA PET is a game changer and superior to choline PET and other established tracers which have been used in prostate cancer evaluation. Detection of recurrence at the prostate bed remains challenging due to bladder and urethral tracer accumulation. The main strength of PSMA PET/CT is its ability to identify small (<8 mm) pathological lymph nodes, upstaging nodal status in up to two-thirds of cases. Additionally, PSMA PET/CT, detects bone and bone marrow metastases missed by conventional bone and CT imaging. Thus, PSMA PET/CT has major impact on patient management, with studies reporting overall changes in 39-76% of cases.

AREAS OF CONTROVERSY

Controversy exists regarding patient access and NHS affordability of PSMA PET/CT imaging. Currently, no reimbursement is available under the NHS tariff system. The cost outlay for tertiary hospital linked PET centres ranges from £150-170 K. Large referral volumes, and technical advances in manufacturing process will make this tracer cost neutral and similar to the current funded, but less sensitive, choline PET. Current NICE guidelines for prostate cancer management do not include a recommendation on when PSMA PET/CT should be used and this is likely to remain the case in the next revision, due in 2019.

GROWING POINTS

Although PSMA PET/CT imaging results in significant management change, there is a need for high quality economic evaluation and cost analysis for this modality. Lack of this data will result in poor adoption of this technique and thus limit patient access. Furthermore, it is hoped that future tracers will become even more sensitive and identify disease at earlier thresholds.

AREAS TIMELY FOR DEVELOPING RESEARCH

Well-designed clinical trials with consideration of the health economic benefit of using PSMA PET/CT will be essential to provide a basis for entry into guidelines such as NICE and to provide a rationale for reimbursement.

Diagnostic Accuracy of 68Ga-PSMA-11 PET/MRI Compared with Multiparametric MRI in the Detection of Prostate Cancer

Purpose To compare the diagnostic accuracy of gallium 68 (⁶⁸Ga)-labeled prostate-specific membrane antigen (PSMA)-11 PET/MRI with that of multiparametric MRI in the detection of prostate cancer. Materials and Methods The authors performed a retrospective study of men with biopsy-proven prostate cancer who underwent simultaneous ⁶⁸Ga-PSMA-11 PET/MRI before radical prostatectomy between December 2015 and June 2017. The reference standard was whole-mount pathologic examination. Readers were blinded to radiologic and pathologic findings. Tumor localization was based on 30 anatomic regions. Region-specific sensitivity and specificity were calculated for PET/MRI and multiparametric MRI by using raw stringent and alternative neighboring approaches. Maximum standardized uptake value (SUV_max) in the tumor and Prostate Imaging Reporting and Data System (PI-RADS) version 2 grade were compared with tumor Gleason score. Generalized estimating equations were used to estimate population-averaged sensitivity and specificity and to determine the association between tumor characteristics and SUV_max or PI-RADS score. Results Thirty-two men (median age, 68 years; interquartile range: 62-71 years) were imaged. The region-specific sensitivities of PET/MRI and multiparametric MRI were 74% (95% confidence interval [CI]: 70%, 77%) and 50% (95% CI: 45%, 0.54%), respectively, with the alternative neighboring approach (P < .001 for both) and 73% (95% CI: 68%, 79%) and 69% (95% CI: 62%, 75%), respectively, with the population-averaged generalized estimating equation (P = .04). Region-specific specificity of PET/MRI was similar to that of multiparametric MRI with the alternative neighboring approach (88% [95% CI: 85%, 91%] vs 90% [95% CI: 87%, 92%], P = .99) and in population-averaged estimates (70% [95% CI: 64%, 76%] vs 70% [95% CI: 64%, 75%], P = .99). SUV_max was associated with a Gleason score of 7 and higher (odds ratio: 1.71 [95% CI: 1.27, 2.31], P < .001). Conclusion The sensitivity of gallium 68-labeled prostate-specific membrane antigen-11 PET/MRI in the detection of prostate cancer is better than that of multiparametric MRI. © RSNA, 2018 See also the editorial by Civelek in this issue.

Can Early Dynamic Positron Emission Tomography/Computed Tomography Obviate the Need for Postdiuresis Image in 68Ga-PSMA-HBED-CC Scan for Evaluation of Prostate Adenocarcinoma?

INTRODUCTION

Forced diuresis technique is often adopted to wash out the high amount of urinary radioactivity that masks the foci of abnormal uptake in the pelvic region on 68Ga-PSMA-HBED-CC positron emission tomography/computed tomography (PET/CT) scan in prostate cancer (PC) patients. However, this method is time-consuming, makes the patient non/less compliant, and is not feasible in patients with renal dysfunction. We hypothesized that early dynamic imaging can obviate the need for a postdiuresis view as the urinary activity is expected to be low at the time.

MATERIALS AND METHODS

A total of 20 biopsy-proven PC patients who were referred to our department for a 68Ga-PSMA PET/CT for staging/restaging were prospectively studied. Dynamic PET/CT was done with on table intravenous (i.v.) injection of 2-3 mCi (74-111 MBq) of the radiotracer. Dynamic images were acquired over the pelvis with a frame time of 1 min for 10 min. Static images of 2 min/bed position were acquired between 45 and 60 min p.i. The patients were then administered i.v. furosemide and encouraged water intake and frequent urination. A static view of pelvic region was acquired at 5 min/bed at 120 min p.i. A three-dimensional volume of interest (3D-VOI) was plotted on the primary lesion, bladder, involved nodes if any, pelvic bones at involved and uninvolved sites, gluteal muscles, and artery. The sentence seems fine. This was to generate the Time activity curve for analysis.

RESULTS

Nine patients were referred for staging and 11 for restaging. Mean age of 20 patients was 64.6 years, and median prostate-specific antigen level was 21.4 ng/ml (range: 0.05-2180). Prostatic lesion was present in 20 patients, nodal involvement in 8, and bone involvement in 10 patients. Median maximum standardized uptake value (SUVmax) of the prostatic lesion (P) showed an ascending trend: 5.31 at 5 min, 10.65 at 60 min, and 10.52 at 120 min p.i. At the same time, median SUVmax of the bladder (B) also progressed steeply and then decreased postdiuresis: 1.01 at 5 min, 24.6 at 60 min, and 6.88 at 120 min. Despite forced diuresis, the bladder activity remained higher than that during early dynamic imaging. Median prostate-to-bladder (P/B) ratio was highest during early dynamic imaging at 5 min p.i. was 5.17, while at 60 min, P/B ratio was 0.42 (P = 0.002) and, at 120 min, it was 1.27 (P = 0.009). Further, all the nodal and bone lesions were clearly visualized on early dynamic images.

CONCLUSION

The study results suggest that early dynamic imaging performs better than a postdiuresis view in terms of delineation of prostatic and regional lesions on 68Ga-PSMA scan. Further, it saves time and the patients are more compliant to this technique.

Application of Cu-64 NODAGA-PSMA PET in Prostate Cancer

INTRODUCTION

The high diagnostic potential of ⁶⁴Cu-PSMA PET-CT imaging was clinically investigated in prostate cancer patients with recurrent disease and in the primary staging of selected patients with advanced local disease. The aim of our study is to assess the uptake behavior in the clinical setting of 64Copper Prostate-Specific Membrane Antigen (⁶⁴Cu PSMA) Positron Emission Tomography/Computed Tomography (PET/CT) in prostate cancer.

METHODS

A retrospective study was performed in 23 patients with intermediate, high risk and progressive disease at primary staging of prostate cancer. All patients underwent ⁶⁴Cu-PSMA PET. Overall, 250 MBq (4 MBq per kg bodyweight, range 230-290 MBq) of ⁶⁴Cu-NODAGA PSMA was intravenously applied. PET images were performed 30 min (pelvis and abdomen) and 1-2 h post-injection (skull base to mid-thigh). Maximum standardized uptake values (SUVmax) were measured in the organs with high physiological uptake such as liver and kidney, and, additionally, background activity was measured in the gluteal area and in suspected tumor lesions using a HERMES workstation.

RESULTS

PSMA uptake was detected in prostate bed in nine patients, in six patients in distant metastases (bone, lung and liver) and in nine patients in lymph nodes. Of 23 patients, 5 (20.8%) did not show any focal pathological uptake in the whole body. The number of sites (prostate bed, lymph nodes, distant metastases) with positive PSMA uptake was significantly associated with PSA values before imaging (P = 0.0032). The ⁶⁴Cu PSMA uptake increased significantly from 30 min to 1-3 h post-injection (Wilcoxon signed rank test, P = 0.002).

CONCLUSIONS

⁶⁴Cu NODAGA-PSMA PET is a promising imaging tool in the detection of residual disease in patients with recurrent or primary progressive prostate cancer. Furthermore, the increased tracer uptake over time indicates in vivo stability of the diagnostic radiopharmaceutical.

Theranostics of prostate cancer: from molecular imaging to precision molecular radiotherapy targeting the prostate specific membrane antigen

Alterations at the molecular level are a hallmark of cancer. Prostate cancer is associated with the overexpression of prostate-specific membrane antigen (PSMA) in a majority of cases, predominantly in advanced tumors, increasing with the grade or Gleason's score. PSMA can be selectively targeted using radiolabeled PSMA ligands. These small molecules binding the PSMA can be radiolabeled with γ-emitters like ^99mTc and ¹¹¹In or positron emitters like ⁶⁸Ga and ¹⁸F for diagnosis as well as with their theranostic pairs such as ¹⁷⁷Lu (β-emitter) or ²²⁵Ac (α-emitter) for therapy. This review summarizes the theranostic role of PSMA ligands for molecular imaging and targeted molecular radiotherapy, moving towards precision oncology.

Quantitative characterisation of clinically significant intra-prostatic cancer by prostate-specific membrane antigen (PSMA) expression and cell density on PSMA-11

OBJECTIVES

To quantitatively characterize clinically significant intra-prostatic cancer (IPC) by prostate-specific membrane antigen (PSMA) expression and cell density on PSMA-11 positron emission tomography/magnetic resonance (PET/MR).

METHODS

Retrospective study approved by the institutional review board with informed written consent obtained. Patients with a solitary, biopsy-proven prostate cancer, Gleason score (GS) ≥7, presenting for initial evaluation by PET/computerised tomography (PET/CT), underwent early prostate PET/MR immediately after PSMA-11 tracer injection. PET/MR [MRI-based attenuation correction (MRAC)] and PET/CT [CT-based AC (CTAC)] maximal standardised uptake value (SUVmax) and minimal and mean apparent diffusion coefficient (ADCmin, ADCmean; respectively) in normal prostatic tissue (NPT) were compared to IPC area. The relationship between SUVmax, ADCmin and ADCmean measurements was obtained.

RESULTS

Twenty-two patients (mean age 69.5±5.0 years) were included in the analysis. Forty-four prostate areas were evaluated (22 IPC and 22 NPT). Median MRAC SUVmax of NPT was significantly lower than median MRAC SUVmax of IPC (p < 0.0001). Median ADCmin and ADCmean of NPT was significantly higher than median ADCmin and ADCmean of IPC (p < 0.0001). A very good correlation was found between MRAC SUVmax with CTAC SUVmax (rho = -0.843, p < 0.0001). A good inverse relationship was found between MRAC SUVmax and CTAC SUVmax with ADCmin (rho = -0.717, p < 0.0001 and -0.740, p < 0.0001; respectively; Z = 0.22, p = 0.82, NS) and with MRAC SUVmax and ADCmean (rho = -0.737, p < 0.0001).

CONCLUSIONS

PET/MR SUVmax, ADCmin and ADCmean are distinct biomarkers able to differentiate between IPC and NPT in naïve prostate cancer patients with GS ≥ 7.

KEY POINTS

• PSMA PET/MR metrics differentiate between normal and tumoural prostatic tissue. • A multi-parametric approach combining molecular and anatomical information might direct prostate biopsy. • PSMA PET/MR metrics are warranted for radiomics analysis.

Oligometastatic prostate cancer and salvage lymph node dissection: systematic review

INTRODUCTION

We provide a comprehensive description of the physio-pathological theories behind oligometastatic prostate cancer (PCa) and analyze modern imaging techniques, presenting a systematic review of the available evidences regarding salvage lymph node dissection (sLND).

EVIDENCE ACQUISITION

A systematic review was attempted. The PubMed/Medline database was searched for "salvage" AND ("lymph node dissection" OR "lymphadenectomy") AND "prostate" AND "cancer." Only English publications were targeted. Relevant original articles addressing the role of sLND in PCa were selected.

EVIDENCE SYNTHESIS

Biochemical response (BR) was reported in 10-79.5% of the cases overall. These results were not durable and biochemical recurrence occurred in 54.5-93.8% of the cases, within 5 years. Furthermore, 50-80% of patients received some kind of adjuvant treatment right after sLND, regardless post-operative prostate-specific antigen levels. Surgery-related morbidity was low, with a 0-27% incidence of Clavien-Dindo III complications. No sLND-related deaths were observed.

CONCLUSIONS

sLND is not associated with a durable response over time but may postpone HT and its related complications, in selected patients. Although a limited morbidity was reported, sLND remains technically demanding and a careful selection of patients is advisable.

Gallium 68 PSMA-11 PET/MR Imaging in Patients with Intermediate- or High-Risk Prostate Cancer

Purpose To report the results of dual-time-point gallium 68 (⁶⁸Ga) prostate-specific membrane antigen (PSMA)-11 positron emission tomography (PET)/magnetic resonance (MR) imaging prior to prostatectomy in patients with intermediate- or high-risk cancer. Materials and Methods Thirty-three men who underwent conventional imaging as clinically indicated and who were scheduled for radical prostatectomy with pelvic lymph node dissection were recruited for this study. A mean dose of 4.1 mCi ± 0.7 (151.7 MBq ± 25.9) of ⁶⁸Ga-PSMA-11 was administered. Whole-body images were acquired starting 41-61 minutes after injection by using a GE SIGNA PET/MR imaging unit, followed by an additional pelvic PET/MR imaging acquisition at 87-125 minutes after injection. PET/MR imaging findings were compared with findings at multiparametric MR imaging (including diffusion-weighted imaging, T2-weighted imaging, and dynamic contrast material-enhanced imaging) and were correlated with results of final whole-mount pathologic examination and pelvic nodal dissection to yield sensitivity and specificity. Dual-time-point metabolic parameters (eg, maximum standardized uptake value [SUV_max]) were compared by using a paired t test and were correlated with clinical and histopathologic variables including prostate-specific antigen level, Gleason score, and tumor volume. Results Prostate cancer was seen at ⁶⁸Ga-PSMA-11 PET in all 33 patients, whereas multiparametric MR imaging depicted Prostate Imaging Reporting and Data System (PI-RADS) 4 or 5 lesions in 26 patients and PI-RADS 3 lesions in four patients. Focal uptake was seen in the pelvic lymph nodes in five patients. Pathologic examination confirmed prostate cancer in all patients, as well as nodal metastasis in three. All patients with normal pelvic nodes in PET/MR imaging had no metastases at pathologic examination. The accumulation of ⁶⁸Ga-PSMA-11 increased at later acquisition times, with higher mean SUV_max (15.3 vs 12.3, P < .001). One additional prostate cancer was identified only at delayed imaging. Conclusion This study found that ⁶⁸Ga-PSMA-11 PET can be used to identify prostate cancer, while MR imaging provides detailed anatomic guidance. Hence, ⁶⁸Ga-PSMA-11 PET/MR imaging provides valuable diagnostic information and may inform the need for and extent of pelvic node dissection.

Predictor of 68Ga PSMA PET/CT positivity in patients with prostate cancer

BACKGROUND

The aim of this study was to evaluate predictive factors of 68Gallium (68Ga) prostate-specific membrane antigen (PSMA) positron emission tomography (PET)/computed tomography (CT) positivity.

METHODS

Relationships between serum prostate specific antigen (PSA), lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) levels, Gleason Score (GS) and positivity of 68Ga PSMA PET in patients who underwent 68Ga PSMA PET/CT for restaging for PCa were evaluated retrospectively.

RESULTS

One hundred and four (median age: 67; range: 51-88) patients were included in this study. Of these patients, PSMA PET was positive in 75 (72%) patients. Mean serum PSA levels for PET negative and positive groups were 0.76±1.00 and 180.85±324.93 ng/mL (P<0.001). The sensitivity and specificity of 68Ga PSMA PET/CT for detection of disease recurrence were calculated as 92% and 80%, respectively, for the 1.4 ng/mL PSA cut-off and 92% and 90%, respectively, for the 2 ng/mL PSA cut-off values. The positivity rates for patients with PSA levels <1.4 ng/mL and ≥1.4 ng/mL were 21% and 90%, respectively (P<0.001).

CONCLUSIONS

68Ga PSMA PET/CT seems to be a highly sensitive in patients with early PSA recurrence. Patients with higher GS and early PSA recurrence could benefit from 68Ga PSMA PET/CT.

The role of 68Ga-PSMA PET/CT scan in biochemical recurrence after primary treatment for prostate cancer: a systematic review of the literature

INTRODUCTION

Recurrence after primary treatment of prostate cancer is one of the major challenges facing urologists. Biochemical recurrence is not rare and occurs in up to one third of the patients undergoing radical prostatectomy. Management of biochemical recurrence is tailored according to the site and the burden of recurrence. Therefore, developing an imaging technique to early detect recurrent lesions represents an urgent need. Positron emission tomography (PET) of 68Ga-labelled prostate-specific membrane antigen (68Ga-PSMA) is an emerging imaging modality that seems to be a promising tool with capability to localize recurrent prostate cancer. A systematic review of literature was done to evaluate the role of 68Ga-PSMA PET/CT scan in patients with recurrent prostate cancer after primary radical treatment.

EVIDENCE ACQUISITION

A systematic and comprehensive review of literature was performed in September 2017 analyzing the MEDLINE and Cochrane Library following the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement. The following key terms were used for the search "PSMA," "prostate-specific membrane antigen," "positron emission tomography," "PET," "recurrent," "prostate cancer," "prostate neoplasm," "prostate malignancy," and "68Ga." Risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool.

EVIDENCE SYNTHESIS

Thirty-seven articles met our inclusion criteria and were included in the analysis of this systematic review. Of the 37 articles selected for analysis only four studies were prospective. The overall detection rate of 68Ga-PSMA PET scan ranged from 47% up to 96.6%. The main advantage of this imaging technique is its relatively high detection rates at low serum PSA levels below 0.5 ng/mL (ranging from 11.1% to 75%). Higher serum PSA level was strongly associated with increased positivity on 68Ga-PSMA PET scan. 68Ga-PSMA PET scan was found superior to conventional imaging techniques (CT and MRI) in this setting of patients and even it seems to outperform choline-based PET scan. This technique provided significant changes in the therapeutic management of 28.6-87.1% of patients.

CONCLUSIONS

After biochemical recurrence, the primary goal is to locate the recurrent lesions' site. 68Ga-PSMA PET/CT seems to be effective in identifying recurrence localization also for very low levels of PSA (<0.5 ng/mL) thus permitting to choose the best therapeutic strategy as early as possible. However, data available cannot be considered exhaustive and prospective randomized trials are needed.

Current application and future perspectives of prostate specific membrane antigen PET imaging in prostate cancer

As precision medicine evolves, the contribution of molecular imaging to the management of prostate cancer (PCa) patients, especially for positron-emission tomography (PET) imaging, is gaining importance. Highly successful approaches to measure the expression of the prostate specific membrane antigen (PSMA) have been introduced recently. PSMA, the glutamate carboxypeptidase II, is a membrane bound metallo-peptidase that is overexpressed in 90-100% of PCa cells. Due to its selective over-expression, PSMA is a reliable tissue marker for prostate cancer and is considered an ideal target for tumor specific imaging and therapy. A variety of PET and SPECT probes targeting this peptide receptor have been introduced. These are undergoing extensive clinical evaluations. Initial results attest to a high accuracy for disease detection compared conventional radiology (CT or MRI) and other nuclear medicine procedure (choline PET or fluciclovine PET). However, prospective evaluation of the impact on patient management for PSMA-ligand PET and its impact on patient outcome is currently missing. Finally, PSMA inhibitors can be radio-labeled with diagnostic (68Ga-PSMA-11), or therapeutic nuclides (177Lu/225Ac PSMA-617) to be used as theranostic agent. Initial results showed that PSMA-targeted radioligand therapy can potentially delay disease progression in metastatic castrate-resistant PCa. This review aims to explore the current application of PSMA based imaging in prostate cancer, reporting about main advantages and limitations of this new theranostic procedure. The future perspectives and potential the applications of this agent will be also discussed.

Effects of Fasting on 18F-DCFPyL Uptake in Prostate Cancer Lesions and Tissues with Known High Physiologic Uptake

In the literature, a 4- to 6-h fast is recommended before a patient undergoes PET/CT with 2-(3-(1-carboxy-5-[(6-¹⁸F-fluoro-pyridine-3-carbonyl)-amino]-pentyl)-ureido)-pentanedioic acid (¹⁸F-DCFPyL); however, a scientific underpinning for this recommendation is lacking. Therefore, we performed a study to determine the impact of fasting on ¹⁸F-DCFPyL uptake. Methods: The study included 50 patients who fasted at least 6 h before ¹⁸F-DCFPyL administration and 50 patients who did not. Activity (SUV_max) was measured in lesions characteristic of prostate cancer and in normal tissues known to express high physiologic uptake. Results: Uptake in suspected lesions did not differ between the cohorts. ¹⁸F-DCFPyL uptake in the submandibular gland, liver, and spleen was significantly higher in the fasting than the nonfasting cohort. Conclusion: Our data show that fasting does not significantly affect ¹⁸F-DCFPyL uptake in suspected malignant lesions but does result in significantly lower ¹⁸F-DCFPyL uptake in tissues with high physiologic uptake. The absolute differences in uptake were relatively small; therefore, the effects of fasting on the diagnostic performance can be considered negligible.

Current status of theranostics in prostate cancer

The aim of this review is to report on the current status of prostate-specific membrane antigen (PSMA)-directed theranostics in prostate cancer (PC) patients. The value of 68Ga-PSMA-directed PET imaging as a diagnostic procedure for primary and recurrent PC as well as the role of evolving PSMA radioligand therapy (PRLT) in castration-resistant (CR)PC is assessed. The most eminent data from mostly retrospective studies currently available on theranostics of prostate cancer are discussed. The current knowledge on 68Ga-PSMA PET/CT implicates that primary staging with PET/CT is meaningful in patients with high-risk PC and that the combination with pelvic multi parametric (mp)MR (or PET/mpMR) reaches the highest impact on patient management. There may be a place for 68Ga-PSMA PET/CT in intermediate-risk PC patients as well, however, only a few data are available at the moment. In secondary staging for local recurrence, 68Ga-PSMA PET/mpMR is superior to PET/CT, whereas for distant recurrence, PET/CT has equivalent results and is faster and cheaper compared to PET/mpMR. 68Ga-PSMA PET/CT is superior to 18F / 11Choline PET/CT in primary staging as well as in secondary staging. In patients with biochemical relapse, PET/CT positivity is directly associated with prostate-specific antigen (PSA) increase and amounts to roughly 50% when PSA is raised to ≤0.5 ng/ml and to ≥90% above 1 ng/ml. Significant clinical results have so far been achieved with the subsequent use of radiolabeled PSMA ligands in the treatment of CRPC. Accumulated activities of 30 to 50 GBq of 177Lu-PSMA ligands seem to be clinically safe with biochemical response and PERCIST/RECIST response in around 75% of patients along with xerostomia in 5-10% of patients as the only notable side effect. On the basis of the current literature, we conclude that PSMA-directed theranostics do have a major clinical impact in diagnosis and therapy of PC patients. We recommend that 68Ga-PSMA PET/CT should be performed in primary staging together with pelvic mpMR in high-risk patients and in all patients for secondary staging, and that PSMA-directed therapy is a potent strategy in CRPC patients when other treatment options have failed. The combination of PSMA-directed therapy with existing therapy modalities (such as 223Ra-chloride or androgen deprivation therapy) has to be explored, and prospective clinical multicenter trials with theranostics are warranted.

Impact of 68Ga-PSMA-PET imaging on target volume definition and guidelines in radiation oncology - a patterns of failure analysis in patients with primary diagnosis of prostate cancer

BACKGROUND

68Ga-PSMA-PET-imaging has proven to be a highly sensitive and specific diagnostic element for patients with prostate cancer (PC). Does the standard clinical target volume (CTV) cover the majority of 68Ga-PSMA-PET detected lymph nodes (LNs) in a primary setting?

METHODS

25 out of 159 patients with primary PC who underwent 68Ga-PSMA-PET-imaging were analyzed in the process of this study. These 25 high-risk patients had a total of 126 LNs with positive 68Ga-PSMA-ligand uptake. A standard CTV according to the 'Radiation Therapy Oncology Group' consensus was delineated and LNs were judged whether they were in- or outside of this target volume. With a Pearson correlation we additionally evaluated whether the Gleason score, the prostate-specific antigen (PSA) value or the risk according to the Roach formula correlate with a higher chance of LNs being outside of the CTV in uncommon LN locations.

RESULTS

81 (64.3%) of 126 LNs were covered by the CTV with a complete coverage of all positive LNs inside the respective radiation volume in 11 of 25 patients (44%). LNs that were not covered by the CTV included (para-aortic,) common-iliac, pre-sacral, obturatoric, para-rectal, para-vesical and pre-acetabular locations. In a statistical analysis neither the Gleason score, nor the PSA value, nor the calculated risk with the Roach formula correlated with LNs being inside or outside of the CTV in this patient group.

CONCLUSION

68Ga-PSMA-PET-imaging proves to be a valuable asset for patients and physicians for primary diagnosis and treatment planning. In our study, trusting the RTOG consensus for CTV delineation would have led to up to 35.7% of all LNs not to be included in the clinical radiation volume, which might have resulted in insufficient radiation dose coverage.

Review of Gallium-68 PSMA PET/CT Imaging in the Management of Prostate Cancer

Over 90% of prostate cancers over-express prostate specific membrane antigen (PSMA) and these tumor cells may be accurately targeted for diagnosis by 68Ga-PSMA-positron emission tomography/computed tomography (68Ga-PSMA-PET/CT) imaging. This novel molecular imaging modality appears clinically to have superseded CT, and appears superior to MR imaging, for the detection of metastatic disease. 68Ga-PSMA PET/CT has the ability to reliably stage prostate cancer at presentation and can help inform an optimal treatment approach. Novel diagnostic applications of 68Ga-PSMA PET/CT include guiding biopsy to improve sampling accuracy, and guiding surgery and radiotherapy. In addition to facilitating the management of metastatic castrate resistant prostate cancer (mCRPC), 68Ga-PSMA can select patients who may benefit from targeted systemic radionuclide therapy. 68Ga-PSMA is the diagnostic positron-emitting theranostic pair with the beta emitter Lutetium-177 PSMA (177Lu-PSMA) and alpha-emitter Actinium-225 PSMA (225Ac-PSMA) which can both be used to treat PSMA-avid metastases of prostate cancer in the molecular tumor-targeted approach of theranostic nuclear oncology.

68Ga-PSMA-HBED-CC Uptake in Cervical, Celiac, and Sacral Ganglia as an Important Pitfall in Prostate Cancer PET Imaging

The study aims to investigate the presence of physiologic prostate-specific membrane antigen (⁶⁸Ga-PSMA)-ligand uptake on PET in cervical, celiac, and sacral ganglia of the sympathetic trunk as a pitfall for lymph node metastases in prostate cancer imaging. Methods: Four hundred seven patients who underwent Glu-NH-CO-NH-Lys radiolabeled with ⁶⁸Ga-gallium N,N-bis[2-hydroxy-5-(carboxyethyl)benzyl]ethylenediamine-N,N-diacetic acid (⁶⁸Ga-PSMA-HBED-CC) PET (combined with a diagnostic CT) were retrospectively analyzed. The number of ⁶⁸Ga-PSMA PET-positive cervical, celiac, and sacral ganglia was determined, and the configuration and SUV_max of each ganglion were measured. In addition, the configuration and SUV_max of adjacent lymph node metastases in the respective region (cervical, celiac, or sacral) were determined. Results:⁶⁸Ga-PSMA-ligand uptake above background was detected in 401 (98.5%) patients in any peripheral ganglia, in 369 (92%) patients in cervical ganglia, in 363 (89%) patients in celiac ganglia, and in 183 (46%) patients in sacral ganglia. The ⁶⁸Ga-PSMA-ligand uptake was highest in celiac (mean SUV_max, 2.9 ± 0.8 vs. cervical mean SUV_max, 2.4 ± 0.6) and sacral (mean SUV_max 1.7 ± 0.5; both P < 0.0001) ganglia. Intraindividually there was a statistically significant but weak to moderate correlation between the ⁶⁸Ga-PSMA-ligand uptake in cervical versus celiac ganglia (R = 0.34, P < 0.0001), cervical versus sacral (R = 0.52, P < 0.0001), and celiac versus sacral (R = 0.16, P < 0.05). The ⁶⁸Ga-PSMA-ligand uptake was significantly more intense in adjacent lymph node metastases than the respective ganglia (cervical: 18.0 ± 16.2 vs. 2.4 ± 0.6, P < 0.0001; celiac: 13.5 ± 12.3 vs. 2.9 ± 0.8, P < 0.0001; sacral: 13.4 ± 11.6 vs. 1.7 ± 0.5, P < 0.0001). Furthermore, ganglia predominantly exhibit a band-shaped configuration (71.2%), followed by a teardrop (26.8%) and only rarely a nodular configuration (2.0%). Conversely, lymph node metastases are only rarely band-shaped (1.1%), but more often show teardrop (40.3%) or nodular appearance (58.6%) (P < 0.00001). Conclusion:⁶⁸Ga-PSMA-ligand uptake in ganglia along the sympathetic trunk as assessed by ⁶⁸Ga-PSMA-HBED-CC PET represents an important pitfall in prostate cancer PET imaging. The ⁶⁸Ga-PSMA-ligand uptake is higher in celiac ganglia than cervical or sacral ganglia, and the level of ⁶⁸Ga-PSMA-ligand uptake seems to be patient-related. For the differentiation between lymph node metastases and sympathetic ganglia, both intensity of ⁶⁸Ga-PSMA-ligand uptake and exact localization and configuration of the respective lesion should be examined carefully.

Trends in oncologic hybrid imaging

Hybrid imaging plays a central role in the diagnosis and management of a wide range of malignancies at all stages. In this article, we review the most pertinent historical developments, emerging clinical applications of novel radiotracers and imaging technologies, and potential implications for training and practice. This includes an overview of novel tracers for prostate, breast, and neuroendocrine tumors, assessment of tumor heterogeneity, the concept of image-guided ‘biologically relevant dosing’, and theranostic applications. Recent technological advancements, including time-of-flight PET, PET/MRI, and ‘one-minute whole-body PET’, are also covered. Finally, we discuss how these rapidly evolving applications might affect current training curricula and how imaging-derived big data could be harnessed to the benefit of our patients.

Impact of 68Ga-PSMA-11 PET/CT on the Management of Prostate Cancer Patients with Biochemical Recurrence

In this prospective survey of referring physicians, we investigated whether and how ⁶⁸Ga-labeled prostate-specific membrane antigen 11 (⁶⁸Ga-PSMA-11) PET/CT affects the implemented management of prostate cancer patients with biochemical recurrence (BCR). Methods: We conducted a prospective survey of physicians (NCT02940262) who referred 161 patients with prostate cancer BCR (median prostate-specific antigen value, 1.7 ng/mL; range, 0.05-202 ng/mL). Referring physicians completed one questionnaire before the scan to indicate the treatment plan without ⁶⁸Ga-PSMA-11 PET/CT information (Q1; n = 101), one immediately after the scan to denote intended management changes (Q2; n = 101), and one 3-6 mo later to document the final implemented management (Q3; n = 56). The implemented management was also obtained via electronic chart review or patient contact (n = 45). Results: A complete documented management strategy (Q1 + Q2 + implemented management) was available for 101 of 161 patients (63%). Seventy-six of these (75%) had a positive ⁶⁸Ga-PSMA-11 PET/CT result. The implemented management differed from the prescan intended management (Q1) in 54 of 101 patients (53%). The postscan intended management (Q2) differed from the prescan intended management (Q1) in 62 of 101 patients (61%); however, these intended changes were not implemented in 29 of 62 patients (47%). Pelvic nodal and extrapelvic metastatic disease on ⁶⁸Ga-PSMA-11 PET/CT (PSMA T0N1M0 and PSMA T0N1M1 patterns) was significantly associated with implemented management changes (P = 0.001 and 0.05). Conclusion: Information from ⁶⁸Ga-PSMA-11 PET/CT brings about management changes in more than 50% of prostate cancer patients with BCR (54/101; 53%). However, intended management changes early after ⁶⁸Ga-PSMA-11 PET/CT frequently differ from implemented management changes.

PSMA-targeted polyinosine/polycytosine vector induces prostate tumor regression and invokes an antitumor immune response in mice

There is an urgent need for an effective treatment for metastatic prostate cancer (PC). Prostate tumors invariably overexpress prostate surface membrane antigen (PSMA). We designed a nonviral vector, PEI-PEG-DUPA (PPD), comprising polyethylenimine-polyethyleneglycol (PEI-PEG) tethered to the PSMA ligand, 2-[3-(1, 3-dicarboxy propyl)ureido] pentanedioic acid (DUPA), to treat PC. The purpose of PEI is to bind polyinosinic/polycytosinic acid (polyIC) and allow endosomal release, while DUPA targets PC cells. PolyIC activates multiple pathways that lead to tumor cell death and to the activation of bystander effects that harness the immune system against the tumor, attacking nontargeted neighboring tumor cells and reducing the probability of acquired resistance and disease recurrence. Targeting polyIC directly to tumor cells avoids the toxicity associated with systemic delivery. PPD selectively delivered polyIC into PSMA-overexpressing PC cells, inducing apoptosis, cytokine secretion, and the recruitment of human peripheral blood mononuclear cells (PBMCs). PSMA-overexpressing tumors in nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice with partially reconstituted immune systems were significantly shrunken following PPD/polyIC treatment, in all cases. Half of the tumors showed complete regression. PPD/polyIC invokes antitumor immunity, but unlike many immunotherapies does not need to be personalized for each patient. The potent antitumor effects of PPD/polyIC should spur its development for clinical use.

Functional and Targeted Lymph Node Imaging in Prostate Cancer: Current Status and Future Challenges

Patients with prostate cancer who have regional lymph node (LN) metastases face an increased risk of death from disease and are therefore treated aggressively. Surgical LN dissection is the established method of staging regional nodes; however, this invasive technique carries substantial morbidities and a noninvasive imaging method is needed to reduce or eliminate the need for extended pelvic LN dissections (ePLND). Conventional computed tomography and magnetic resonance (MR) imaging have proven insensitive and nonspecific because both use nodal size criteria, which is notoriously inaccurate. Novel imaging techniques such as functional MR imaging by using diffusion-weighted MR imaging, MR lymphography with iron oxide particles, and targeted positron emission tomography imaging are currently under development and appear to improve LN staging of prostate cancer. Although progress is being made in staging nodes with imaging, it has not reached the point of replacing ePLND. In this review, the strengths and limitations of these new functional and targeted LN imaging techniques for prostate cancer are discussed. ^© RSNA, 2017.

68Ga-PSMA-11 PET/CT Mapping of Prostate Cancer Biochemical Recurrence After Radical Prostatectomy in 270 Patients with a PSA Level of Less Than 1.0 ng/mL: Impact on Salvage Radiotherapy Planning

Target volume delineations for prostate cancer (PCa) salvage radiotherapy (SRT) after radical prostatectomy are usually drawn in the absence of visibly recurrent disease. ⁶⁸Ga-labeled prostate-specific membrane antigen (PSMA-11) PET/CT detects recurrent PCa with sensitivity superior to standard-of-care imaging at serum prostate-specific antigen (PSA) values low enough to affect target volume delineations for routine SRT. Our objective was to map the recurrence pattern of PCa early biochemical recurrence (BCR) after radical prostatectomy with ⁶⁸Ga-PSMA-11 PET/CT in patients with serum PSA levels of less than 1 ng/mL, determine how often consensus clinical target volumes (CTVs) based on the Radiation Therapy Oncology Group (RTOG) guidelines cover ⁶⁸Ga-PSMA-11 PET/CT-defined disease, and assess the potential impact of ⁶⁸Ga-PSMA-11 PET/CT on SRT. Methods: This was a post hoc analysis of an intention-to-treat population of 270 patients who underwent ⁶⁸Ga-PSMA-11 PET/CT at 4 institutions for BCR after prostatectomy without prior radiotherapy at a PSA level of less than 1 ng/mL. RTOG consensus CTVs that included both the prostate bed and the pelvic lymph nodes were contoured on the CT dataset of the PET/CT image by a radiation oncologist masked to the PET component. ⁶⁸Ga-PSMA-11 PET/CT images were analyzed by a nuclear medicine physician. ⁶⁸Ga-PSMA-11-positive lesions not covered by planning volumes based on the consensus CTVs were considered to have a potential major impact on treatment planning. Results: The median PSA level at the time of ⁶⁸Ga-PSMA-11 PET/CT was 0.48 ng/mL (range, 0.03-1 ng/mL). One hundred thirty-two of 270 patients (49%) had a positive ⁶⁸Ga-PSMA-11 PET/CT result. Fifty-two of 270 (19%) had at least one PSMA-11-positive lesion not covered by the consensus CTVs. Thirty-three of 270 (12%) had extrapelvic PSMA-11-positive lesions, and 19 of 270 (7%) had PSMA-11-positive lesions within the pelvis but not covered by the consensus CTVs. The 2 most common ⁶⁸Ga-PSMA-11-positive lesion locations outside the consensus CTVs were bone (23/52, 44%) and perirectal lymph nodes (16/52, 31%). Conclusion: Post hoc analysis of ⁶⁸Ga-PSMA-11 PET/CT implied a major impact on SRT planning in 52 of 270 patients (19%) with PCa early BCR (PSA < 1.0 ng/mL). This finding justifies a randomized imaging trial of SRT with or without ⁶⁸Ga-PSMA-11 PET/CT investigating its potential benefit on clinical outcome.

68Gallium-Prostate-Specific Membrane Antigen PET/Computed Tomography for Primary and Secondary Staging in Prostate Cancer

Prostate-specific membrane antigen (PSMA) PET has been recently introduced for the diagnosis of patients with metastatic prostate cancer (PCa). Until today, staging of patients with PCa relied mostly on morphologic features, such as size or shape, resulting in low detection rates in disease recurrence. PSMA PET imaging provides molecular information and, in combination with conventional imaging, offers improved sensitivity and specificity. This review discusses the benefits and limitations of PSMA imaging in the setting of primary staging and detection of recurrent disease in comparison with standard-of-care imaging techniques.

Prostate Cancer Molecular Imaging Standardized Evaluation (PROMISE): Proposed miTNM Classification for the Interpretation of PSMA-Ligand PET/CT

Prostate-specific membrane antigen (PSMA)-ligand PET imaging provides unprecedented accuracy for whole-body staging of prostate cancer. As PSMA-ligand PET/CT is increasingly adopted in clinical trials and routine practice worldwide, a unified language for image reporting is urgently needed. We propose a molecular imaging TNM system (miTNM, version 1.0) as a standardized reporting framework for PSMA-ligand PET/CT or PET/MRI. miTNM is designed to organize findings in comprehensible categories to promote the exchange of information among physicians and institutions. Additionally, flowcharts integrating findings of PSMA-ligand PET and morphologic imaging have been designed to guide image interpretation. Specific applications, such as assessment of prognosis or impact on management, should be evaluated in future trials. miTNM is a living framework that evolves with clinical experience and scientific data.

Salvage lymph node dissection after 68Ga-PSMA or 18F-FEC PET/CT for nodal recurrence in prostate cancer patients

The management of patients with biochemical recurrence (BCR) after definitive treatment for prostate cancer remains controversial. Our aim was to determine survival rates and complications of salvage lymph node dissection (sLND) in patients with recurrent prostate cancer after radical prostatectomy, while evaluating biochemical response (BR) with two different positron emission tomography/computed tomography (PET/CT) tracers used for preoperative imaging. sLND was performed in 104 patients diagnosed with isolated nodal recurrence on either ¹⁸F-fluoroethylcholine (¹⁸F-FEC) or ⁶⁸Ga-PSMA-HBED-CC (⁶⁸Ga-PSMA) PET/CT. Surgical complications, BR, clinical recurrence (CR), and cancer-specific survival (CSS) were evaluated. Logistic regression was used to determine predictors of complete BR (cBR) and CR after sLND and survival rates were assessed. Median follow-up was 39.5 months. Median patient age and prostate-specific antigen (PSA) at sLND were 64 years and 4.1 ng/mL. Median number of lymph nodes (LNs) removed was 13; median number of positive LNs was 3 per patient. Rate of Clavien-Dindo Grade III complications was low (4.8%). 29.8% of patients developed cBR (PSA < 0.2 ng/mL), and 56.7% partial BR (PSA postoperative < PSA preoperative) after sLND. Patients with LN metastases diagnosed on ⁶⁸Ga-PSMA PET/CT showed a higher rate of cBR compared to ¹⁸F-FEC PET/CT (45.7 vs. 21.7%, p = 0.040). PSA at sLND (p = 0.031) and choice of PET tracer (p = 0.048) were independent predictors of cBR. The 5-year BCR-free, CR-free and CSS rates were 6.2%, 26.0%, and 82.8%, respectively. While preoperative staging with ⁶⁸Ga-PSMA seems superior, only a limited number of patients developed cBR after surgery. Most patients experienced BCR and CR during follow-up.