Performance characteristics of computed tomography in detecting lymph node metastases in contemporary patients with prostate cancer treated with extended pelvic lymph node dissection

Whole-body MRI for staging prostate cancer: a narrative review

OBJECTIVE

To present a narrative review regarding the diagnostic accuracy of whole-body magnetic resonance imaging (WBMRI) in staging patients with high-risk prostate cancer (HRPCa) and compare it to established imaging modalities.

METHODS

A narrative review was carried out using PubMed using the following keywords: 'whole body', 'magnetic resonance imaging', 'MRI', 'prostate cancer', 'risk stratification', and 'staging'. Articles that evaluated WBMRI as the imaging modality to stage patients with HRPCa were included, while studies that solely assessed for biochemical recurrence or metastatic disease progression were excluded.

RESULTS

In the evaluation of lymphatic metastases, WBMRI has demonstrated a comparable, if not improved, sensitivity and specificity compared to conventional imaging of computed tomography (CT). Furthermore, WBMRI demonstrates improved sensitivity and specificity in detecting bone metastases compared to bone scintigraphy (BS). However, with advent of prostate-specific membrane antigen (PSMA) radioligands for positron emission tomography (PET), the diagnostic performance of WBMRI to detect metastatic disease appears inferior.

CONCLUSIONS

The diagnostic capabilities of WBMRI exceed that of conventional imaging of CT and BS in detecting metastatic disease in patients with HRPCa. However, WBMRI does not perform as well as PSMA PET/CT. Further study on cost comparisons between WBMRI and PSMA PET/CT are needed, as well as evaluations of combined PSMA PET/MRI are needed.

Whole-body magnetic resonance imaging for staging patients with high-risk prostate cancer

BACKGROUND

Staging patients with high-risk prostate cancer (HRPCa) with conventional imaging of computed tomography (CT) and bone scintigraphy (BS) is suboptimal. Therefore, we aimed to compare the accuracy of whole-body magnetic resonance imaging (WBMRI) with conventional imaging to stage patients with HRPCa.

METHODS

We prospectively enrolled patients with newly diagnosed HRPCa (prostate-specific antigen ≥20 ng/ml and/or Grade Group ≥4). Patients underwent BS, CT of the abdomen and pelvis, and WBMRI within 30 days of evaluation. The primary endpoint was the diagnostic performances of detecting metastatic disease to the lymph nodes and bone for WBMRI and conventional imaging. The reference standard was defined by histopathology or by all available clinical information at 6 months of follow-up. To compare diagnostic tests, Exact McNemar's test and area under the curve (AUC) of the receiver operating characteristics curves were utilized.

RESULTS

Among 92 patients enrolled, 15 (16.3%) and 8 (8.7%) patients were found to have lymphatic and bone metastases, respectively. The sensitivity, specificity, and accuracy of WBMRI in detecting lymphatic metastases were 0.60 (95% confidence interval 0.32-0.84), 0.84 (0.74-0.92), and 0.80 (0.71-0.88), respectively, while CT were 0.20 (0.04-0.48), 0.92 (0.84-0.97), and 0.80 (0.71-0.88). The sensitivity, specificity, and accuracy of WBMRI to detect bone metastases were 0.25 (0.03-0.65), 0.94 (0.87-0.98), and 0.88 (0.80-0.94), respectively, while CT and BS were 0.12 (0-0.53), 0.94 (0.87-0.98), and 0.87 (0.78-0.93). For evaluating lymphatic metastases, WBMRI demonstrated a higher sensitivity (p = 0.031) and discrimination compared to CT (0.72 versus 0.56, p = 0.019).

CONCLUSIONS

For staging patients with HRPCa, WBMRI outperforms CT in the detection of lymphatic metastases and performs as well as CT and BS in the detection of bone metastases. Further studies are needed to assess the cost effectiveness of WBMRI and the utility of combined PSMA PET and WBMRI.

Current status and therapeutic value of extended pelvic lymph node dissection during radical prostatectomy for prostate cancer

Pelvic lymph node dissection (PLND) is important for accurate staging and prognosis of prostate cancer. Several guidelines recommend extended pelvic lymph node dissection (ePLND) for patients with non-low-risk prostate cancer. However, the therapeutic benefits of ePLND are unclear. Therefore, we reviewed the literature regarding the therapeutic value of PLND for prostate cancer. Although some reports showed that ePLND improves postoperative biochemical recurrence and postoperative overall survival compared with limited lymph node dissection, other reports show no benefits. Overall, the current evidence supporting ePLND is poor. The extent of PLND varied among studies concerning the therapeutic value of ePLND, and study design issues such as patient background and length of follow-up period were different. Some reports demonstrated potential therapeutic value for ePLND when adjusting for patient background. Focusing on patients with high-grade prostate cancer may be important in demonstrating the therapeutic benefits of ePLND. Although the incidence of major adverse events related to ePLND was low, the possibility of adverse events such as lymphedema and lymphocele formation should be considered. In the future, we hope that evidence for optimal selection criteria for ePLND and the extent of ePLND will become more definitive and evidence for the therapeutic value of ePLND will be developed.

Comparison of discovery rates and prognostic utility of [68Ga]Ga-PSMA-11 PET/CT and circulating tumor DNA in prostate cancer-a cross-sectional study

BACKGROUND

Circulating-tumor DNA (ctDNA) and prostate-specific membrane antigen (PSMA) ligand positron-emission tomography (PET) enable minimal-invasive prostate cancer (PCa) detection and survival prognostication. The present study aims to compare their tumor discovery abilities and prognostic values.

METHODS

One hundred thirty men with confirmed PCa (70.5 ± 8.0 years) who underwent [68Ga]Ga-PSMA-11 PET/CT (184.8 ± 19.7 MBq) imaging and plasma sample collection (March 2019-August 2021) were included. Plasma-extracted cell-free DNA was subjected to whole-genome-based ctDNA analysis. PSMA-positive tumor lesions were delineated and their quantitative parameters extracted. ctDNA and PSMA PET/CT discovery rates were compared, and the prognostic value for overall survival (OS) was evaluated.

RESULTS

PSMA PET discovery rates according to castration status and PSA ranges did differ significantly (P = 0.013, P < 0.001), while ctDNA discovery rates did not (P = 0.311, P = 0.123). ctDNA discovery rates differed between localized and metastatic disease (P = 0.013). Correlations between ctDNA concentrations and PSMA-positive tumor volume (PSMA-TV) were significant in all (r = 0.42, P < 0.001) and castration-resistant (r = 0.65, P < 0.001), however not in hormone-sensitive patients (r = 0.15, P = 0.249). PSMA-TV and ctDNA levels were associated with survival outcomes in the Logrank (P < 0.0001, P < 0.0001) and multivariate Cox regression analysis (P = 0.0023, P < 0.0001).

CONCLUSION

These findings suggest that PSMA PET imaging outperforms ctDNA analysis in detecting prostate cancer across the whole spectrum of disease, while both modalities are independently highly prognostic for survival outcomes.

PSMA PET for Detection of Recurrence

Prostate cancer (PC) is a significant health concern worldwide, with high incidence and mortality rates. Early and accurate detection and localization of recurrent disease at biochemical recurrence (BCR) is critical for guiding subsequent therapeutic decisions and improving patient outcomes. At BCR, conventional imaging consisting of CT, MRI, and bone scintigraphy are recommended by US and European guidelines, however, these modalities all bear certain limitations in detecting metastatic disease, particularly in low-volume relapse at low prostate-specific antigen (PSA) levels. Molecular imaging with PET/CT or PET/MRI using prostate-specific membrane antigen (PSMA) targeting radiopharmaceuticals has revolutionized imaging of PC. Particularly at BCR PC, PSMA PET has shown better diagnostic performance compared to conventional imaging in detecting local relapse and metastases, even at very low PSA levels. The most recent version of the National Comprehensive Cancer Network (NCCN) guideline has included PSMA-targeted PET/CT or PET/MRI for the localization of BCR PC. There are several different PSMA-targeting radiopharmaceuticals labeled with different radioisotopes, each with slightly different characteristics, but overall similar high sensitivity and specificity for PC. PSMA-targeted PET has the potential to significantly impact patient care by guiding personalized treatment decisions and thus improving outcomes in BCR PC patients.

18F-FDG PET Is Not Inferior to 68Ga-PSMA PET for Detecting Biochemical Recurrent Prostate Cancer with a High Gleason Score: A Head-to-Head Comparison Study

Previous studies have indicated that 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in biochemical recurrence (BCR) patients with poorly differentiated prostate adenocarcinoma had higher diagnostic sensitivity than those with well differentiated adenocarcinoma, but whether the performance of FDG PET can achieve the effect of prostate-specific membrane antigen (PSMA) PET in BCR patients with a high Gleason score remains poorly understood. This study aimed to compare the efficacies of 18F-FDG PET/CT and 68Ga-PSMA PET/CT for BCR patients and evaluate whether 18F-FDG PET was not inferior to 68Ga-PSMA PET for detecting BCR with a high Gleason score. This was a retrospective, head-to-head comparative study completed at Ren Ji Hospital between May 2018 and June 2021. Patients underwent both 18F-FDG and 68Ga-PSMA PET/CT. The detection rate of BCR at the patient level and at the anatomical region level was evaluated. In total, 145 patients were enrolled in this study. 18F-FDG PET/CT (24.1%, 35/145) had lower detection rates than 68Ga-PSMA PET/CT (59.3%, 86/145; p < 0.001) at the patient level and at any anatomical region (p < 0.05). The PSA level (p < 0.001, OR = 11.026, 95% CI: 3.214-37.824) and the Gleason score (p < 0.001, OR = 20.227, 95% CI: 5.741-71.267) were independent predictive factors of the detection rate on 18F-FDG PET/CT, while the PSA level (p < 0.001, OR = 4.862, 95% CI: 2.338-10.110) was the only predictor of the detection rate on 68Ga-PSMA PET/CT. 18F-FDG PET/CT had a similar detection rate as 68Ga-PSMA PET/CT in patients with a Gleason score of 9 at the patient level (64.3% vs. 71.4%, p = 0.567) and any anatomical region (all p > 0.05), but 18F-FDG PET/CT had a lower detection rate than 68Ga-PSMA PET/CT in patients with a Gleason score of 6-8. 18F-FDG PET is not inferior to 68Ga-PSMA PET for detecting BCR with a Gleason score of 9; therefore, 18F-FDG PET/CT could be considered in BCR patients with a Gleason score of 9. However, 68Ga-PSMA is a better tracer than 18F-FDG in PET/CT for treatment decision making in BCR patients with a Gleason score of 6-8.

Identification of the Optimal Candidates for Nodal Staging with Extended Pelvic Lymph Node Dissection Among Prostate Cancer Patients Who Underwent Preoperative Prostate-specific Membrane Antigen Positron Emission Tomography. External Validation of the Memorial Sloan Kettering Cancer Center and Briganti Nomograms and Development of a Novel Tool

BACKGROUND

Although the therapeutic role of extended pelvic lymph node dissection (ePLND) in patients with prostate cancer (PCa) is still under debate, this procedure is recommended for staging purposes in selected cases. Nomograms for predicting lymph node invasion (LNI) do not account for prostate-specific membrane antigen (PSMA) positron emission tomography (PET) imaging, which is characterized by a high negative predictive value for nodal metastases.

OBJECTIVE

To externally validate models predicting LNI in patients with miN0M0 PCa at PSMA PET and to develop a novel tool in this setting.

DESIGN, SETTING, AND PARTICIPANTS

Overall, 458 patients with miN0M0 disease undergoing radical prostatectomy (RP) and ePLND at 12 centers between 2017 and 2022 were identified.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSES

Available tools were externally validated using calibration plots, the area under the receiver operating characteristic curve (AUC), and decision curve analyses to assess calibration, discrimination, and the net benefit. A novel coefficient-based model was developed, internally validated, and compared with available tools.

RESULTS AND LIMITATIONS

Overall, 53 patients (12%) had LNI. The AUC was 69% for the Briganti 2012, 64% for the Briganti 2017, 73% for the Briganti 2019, and 66% for the Memorial Sloan Kettering Cancer Center nomogram. Multiparametric magnetic resonance imaging stage, biopsy grade group 5, the diameter of the index lesion, and the percentage of positive cores at systematic biopsy were independent predictors of LNI (all p ≤ 0.04). Internal cross-validation confirmed a coefficient-based model with AUC of 78%, better calibration, and a higher net benefit in comparison to the other nomograms assessed. Use of a 5% cutoff would have spared 47% ePLND procedures (vs 13% for the Briganti 2019 nomogram) at the cost of missing only 2.1% LNI cases . The lack of central review of imaging and pathology represents the main limitation.

CONCLUSIONS

Tools for predicting LNI are associated with suboptimal performance for men with miN0M0 PCa. We propose a novel model for predicting LNI that outperforms available tools in this population.

PATIENT SUMMARY

Tools currently used to predict lymph node invasion (LNI) in prostate cancer are not optimal for men with negative node findings on PET (positron emission tomography) scans, leading to a high number of unnecessary extended pelvic lymph node dissection (ePLND) procedures. A novel tool should be used in clinical practice to identify candidates for ePLND to reduce the risk of unnecessary procedures without missing LNI cases.

Traditional and novel imaging modalities for advanced prostate cancer: A critical review

Accurate detection of metastatic prostate cancer in the setting of preoperative staging as well as posttreatment recurrence is crucial to provide patients with appropriate and timely treatment of their disease. This has traditionally been accomplished with a combination of computed tomography, magnetic resonance imaging, and bone scan. Recently, more novel imaging techniques have been developed to help improve the detection of advanced and metastatic prostate cancer. This review discusses the efficacy of the traditional imaging modalities as well as the novel imaging techniques in detecting metastatic prostate cancer. Articles discussed were gathered through a formal PubMed search.

Negative predictive value of PSMA PET scan for lymph node staging in patients undergoing robotic radical prostatectomy and pelvic lymph node dissection

PURPOSE

To assess the negative predictive value of PSMA PET scan for lymph node staging in patients undergoing robotic radical prostatectomy and pelvic lymph node dissection.

MATERIALS AND METHODS

A retrospective analysis of patients who underwent robotic-assisted radical prostatectomy with pelvic lymph node dissection and had a preoperative negative PSMA PET scan for metastasis was performed. The documented pre-operative variables studied included age, BMI, PSA at diagnosis, Gleason score, and biopsy ISUP grades. Patients were categorised as low, intermediate and high risk according to the D Amico classification. The post-op variables included were number of lymph nodes harvested, number of positive nodes, positivity rate, size of the node metastasis, T staging and ISUP grading.

RESULTS

The overall negative predictive value of PSMA PET scan was 71.6%. Further sub-classification according to risk stratification demonstrated a NPV of 58.02%, 92.7% and 90% for high, intermediate and low risk, respectively.

CONCLUSION

Pelvic lymph node dissection cannot be excluded based on a negative preop PSMA PET/CT scan.

Sentinel Node Procedure to Select Clinically Localized Prostate Cancer Patients with Occult Nodal Metastases for Whole Pelvis Radiotherapy

Background

Accurate identification of men who harbor nodal metastases is necessary to select patients who most likely benefit from whole pelvis radiotherapy (WPRT). Limited sensitivity of diagnostic imaging approaches for the detection of nodal micrometastases has led to the exploration of the sentinel lymph node biopsy (SLNB).

Objective

To evaluate whether SLNB can be used as a tool to select pathologically node-positive patients who likely benefit from WPRT.

Design setting and participants

We included 528 clinically node-negative primary prostate cancer (PCa) patients with an estimated nodal risk of >5% treated between 2007 and 2018.

Intervention

A total of 267 patients were directly treated with prostate-only radiotherapy (PORT; non-SLNB group), while 261 patients underwent SLNB to remove lymph nodes directly draining from the primary tumor prior to radiotherapy (SLNB group); pN0 patients were treated with PORT, while pN1 patients were offered WPRT.

Outcome measurements and statistical analysis

Biochemical recurrence-free survival (BCRFS) and radiological recurrence-free survival (RRFS) were compared using propensity score weighted (PSW) Cox proportional hazard models.

Results and limitations

The median follow-up was 71 mo. Occult nodal metastases were found in 97 (37%) SLNB patients (median metastasis size: 2 mm). Adjusted 7-yr BCRFS rates were 81% (95% confidence interval [CI] 77-86%) in the SLNB group and 49% (95% CI 43-56%) in the non-SLNB group. The corresponding adjusted 7-yr RRFS rates were 83% (95% CI 78-87%) and 52% (95% CI 46-59%), respectively. In the PSW multivariable Cox regression analysis, SLNB was associated with improved BCRFS (hazard ratio [HR] 0.38, 95% CI 0.25-0.59, p < 0.001) and RRFS (HR 0.44, 95% CI 0.28-0.69, p < 0.001). Limitations include the bias inherent to the study's retrospective nature.

Conclusions

SLNB-based selection of pN1 PCa patients for WPRT was associated with significantly improved BCRFS and RRFS compared with (conventional) imaging-based PORT.

Patient summary

Sentinel node biopsy can be used to select patients who will benefit from the addition of pelvis radiotherapy. This strategy results in a longer duration of prostate-specific antigen control and a lower risk of radiological recurrence.

Prediction of pelvic lymph node metastases and PSMA PET positive pelvic lymph nodes with multiparametric MRI and clinical information in primary staging of prostate cancer

Purpose

To compare the accuracy of multiparametric MRI (mpMRI), ⁶⁸Ga-PSMA PET and the Briganti 2019 nomogram in the prediction of metastatic pelvic lymph nodes (PLN) in prostate cancer, to assess the accuracy of mpMRI and the Briganti nomogram in prediction of PET positive PLN and to investigate the added value of quantitative mpMRI parameters to the Briganti nomogram.

Method

This retrospective IRB-approved study included 41 patients with prostate cancer undergoing mpMRI and ⁶⁸Ga-PSMA PET/CT or MR prior to prostatectomy and pelvic lymph node dissection. A board-certified radiologist assessed the index lesion on diffusion-weighted (Apparent Diffusion Coefficient, ADC; mean/volume), T2-weighted (capsular contact length, lesion volume/maximal diameters) and contrast-enhanced (iAUC, k_ep, K^trans, v_e) sequences. The probability for metastatic pelvic lymph nodes was calculated using the Briganti 2019 nomogram. PET examinations were evaluated by two board-certified nuclear medicine physicians.

Results

The Briganti 2019 nomogram performed superiorly (AUC: 0.89) compared to quantitative mpMRI parameters (AUCs: 0.47-0.73) and ⁶⁸Ga-PSMA-11 PET (AUC: 0.82) in the prediction of PLN metastases and superiorly (AUC: 0.77) in the prediction of PSMA PET positive PLN compared to MRI parameters (AUCs: 0.49-0.73). The addition of mean ADC and ADC volume from mpMRI improved the Briganti model by a fraction of new information of 0.21.

Conclusions

The Briganti 2019 nomogram performed superiorly in the prediction of metastatic and PSMA PET positive PLN, but the addition of parameters from mpMRI can further improve its accuracy. The combined model could be used to stratify patients requiring ePLND or PSMA PET.

Accuracy of PET-choline in nodal staging of localized very high-risk prostate cancer

OBJECTIVES

Localized very high-risk prostate cancer (VHR PCa) has long suffered from the inex-istence of good lymph node staging methods other than invasive surgery, as computed tomogra-phy has low sensitivity for nodal disease. With the rising use of positron emission tomography (PET), it is clinically meaningful to know its value for these patients. Our goal was to evaluate the real-life diagnostic accuracy of PET Choline in nodal staging, comparing it with the gold standard of extended pelvic lymph node dissection (ePLND).

MATERIALS AND METHODS

We reviewed data from a high-volume center, including patients with VHR PCa according to current NCCN guidelines who underwent community 18F-fluorocholine PET/CT; followed by ro-botic assisted laparoscopic prostatectomy (RALP) and ePLND between 2010 and 2021.

RESULTS

We included 44 patients and 88 lymph node regions. Among those, 14/44 (31.8%) patients and 20/88 (22.7%) regions had nodal disease present on definitive pathology. In comparison with ePLND, we found a sensitivity of 64.3% (95% CI, 39.2-89.4%), specificity of 83.3% (95% CI, 70.0- 96.7%), PPV of 64.3% (95% CI, 39.2-89.4%), and NPV of 83.3% (95% CI, 70.0-96.7%) for nodal disease on a patient-based analysis; and sensitivity of 35.0% (95% CI, 14.1-60.0%), specificity of 88.2% (95% CI, 80.6-95.9%), PPV of 46.7% (95% CI, 21.4-71.9%), and NPV of 82.2% (95% CI, 73.4-91.0%) on a region-based analysis.

CONCLUSIONS

In our view 18F-fluorocholine PET/CT doesn't meet the criteria to be a standard exam for pre-operative staging for patients with VHR PCa, mostly due to its low sensitivity. However, other radiotracers should continue to be investigated in this setting.

Calibrated Regression Models Based on the Risk of Clinical Nodal Metastasis Should be Used as Decision Aids for Prostate Cancer Staging to Reduce Unnecessary Imaging

INTRODUCTION

Radionuclide imaging will change the role of computed tomography and magnetic resonance imaging (CT/MRI) for prostate cancer (CaP) staging. Current guidelines recommend abdominopelvic imaging for new cases of CaP categorized as unfavorable intermediate risk (UIR) or higher. We assessed the performance characteristics of CT/MRI based on the National Comprehensive Cancer Network (NCCN) guidelines and developed a model that predicts cN1 disease using conventional imaging.

PATIENTS AND METHODS

We selected patients in the National Cancer Database diagnosed with CaP from 2010 to 2016 with available age, prostate specific antigen, clinical locoregional staging, biopsy Gleason grading, and core information. Multivariate logistic regression (MLR) was used on a undersampled training dataset using cN1 as the outcome. Performance characteristics were compared to those of the three most recent versions of the NCCN guidelines.

RESULTS

A total of 443,640 men were included, and 2.5% had cN1 disease. Using CT/MRI only, the current NCCN guidelines have a sensitivity of 99%, and the number needed to image (NNI) is 24. At the same sensitivity, the cN1 risk was 1.6% using the MLR. The NNI for UIR alone is 341. Using the MLR model and a threshold of 10%, the PPV is 10.3% and 64% of CTs/MRIs could be saved at a cost of missing 6% of cN1 patients (or 0.15% of all patients).

CONCLUSION

The NCCN guidelines are sensitive for detecting cN1 with CT/MRI, however, the number needed to image is 24. Obtaining CT/MRI for nodal staging when patients have a cN1 risk of 10% would reduce total imaging while still remaining sensitive. As novel PET tracers becomes increasingly used for initial CaP staging, well calibrated prediction models trained on the outcome of interest should be developed as decision aids for obtaining imaging.

Complications of Extended Pelvic Lymph Node Dissection in Patients Undergoing Minimally Invasive Radical Prostatectomy: Analysis and Risk Factors

Background

The knowledge of risk factors and complications related to extended pelvic lymph node dissection (ePLND) during radical prostatectomy can help selecting patients who will benefit the most with lymph node dissection concomitant to radical prostatectomy.

Materials and Methods

Retrospective cohort evaluating 135 patients with PC, with a high risk for lymph node metastasis, submitted to ePLND by a single surgeon between 2013 and 2019, performed either by the laparoscopic or laparoscopic robot-assisted approach. Data related to complications were properly recorded using the Martin's criteria and were classified by the Satava and Clavien–Dindo–Strasberg methods. Logistic regression was used to determine predictors of complications related to ePLND.

Results

The mean number of lymph nodes removed was 10.2 ± 4.9, and in 28.2%, they were positive for metastasis. There were five intraoperative complications (4%), all in patients operated by laparoscopic approach. There were nine severe postoperative complications (7.3%), four of which occurred after postoperative day 30. Three patients (2.4%) had thromboembolic complications and five patients (4.0%) had lymphocele that required treatment. There was a correlation between the American Society of Anesthesiologists (ASA) physical status classification and postoperative complications (p=0.06), but it was not possible to identify statistically significant predictors.

Conclusion

ePLND during radical prostatectomy has a low rate of intraoperative complications and may change prostate cancer staging. Postoperative complications, especially venous thromboembolism and lymphocele, need to be monitored even in the late postoperative period.

Modern paradigms for prostate cancer detection and management

Early detection and management of prostate cancer has evolved over the past decade, with a focus now on harm minimisation and reducing overdiagnosis and overtreatment, given the proven improvements in survival from randomised controlled trials. Multiparametric magnetic resonance imaging (mpMRI) is now an important aspect of the diagnostic pathway in prostate cancer, improving the detection of clinically significant prostate cancer, enabling accurate localisation of appropriate sites to biopsy, and reducing unnecessary biopsies in most patients with normal magnetic resonance imaging scans. Biopsies are now performed transperineally, substantially reducing the risk of post-procedure sepsis. Australian-led research has shown that prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) has superior accuracy in the staging of prostate cancer than conventional imaging (CT and whole-body bone scan). Localised prostate cancer that is low risk (International Society for Urological Pathology [ISUP] grade 1, Gleason score 3 + 3 = 6; and ISUP grade group 2, Gleason score 3 + 4 = 7 with less than 10% pattern 4) can be offered active surveillance, reducing harms from overtreatment. Prostatectomy and definitive radiation remain the gold standard for localised intermediate and high risk disease. However, focal therapy is an emerging experimental treatment modality in Australia in carefully selected patients. The management of advanced prostate cancer treatment has evolved to now include several novel agents both in the metastatic hormone-sensitive and castration-resistant disease settings. Multimodal therapy with androgen deprivation therapy, additional systemic therapy and radiotherapy are often recommended. PSMA-based radioligand therapy has emerged as a treatment option for metastatic castration-resistant prostate cancer and is currently being evaluated in earlier disease states.

The value of 68 Ga-PSMA-11 PET/CT in patients with prostate cancer and inconclusive standard imaging at primary staging

OBJECTIVE

The current standard imaging recommended for primary staging of intermediate- and high-risk prostate cancer (PCa) consists of bone scintigraphy (BS) and computed tomography (CT). Some patients will have equivocal lesions or divergent findings on BS and CT, leading to inconclusive disease staging. Our aim was to investigate the value of 68 Ga-PSMA-11 PET/CT in PCa with inconclusive disease stage based on standard imaging.

METHODS

We made a single-center study of patients with newly diagnosed PCa who underwent a 68 Ga-PSMA-11 PET/CT due to equivocal findings or discrepancies between BS and CT from 1 January 2017 to 31 December 2020. The value of 68 Ga-PSMA-11 PET/CT was evaluated for each location of equivocal findings (regional lymphnode, nonregional lymphnodes, bones and other metastases) and on a patient level.

RESULTS

Seventy-six patients were included in the study (62 patients with 72 equivocal lesions, 14 with discrepancy between BS and CT). Equivocal lesions were predominately in the bones (61%, 44/72), or in the regional lymph nodes (17%, 12/72). 68 Ga-PSMA-11 PET/CT provided a conclusive diagnosis in 90% (65/72) of the equivocal lesions. All patients with discrepancies between BS and CT had definite answers after 68 Ga-PSMA-11 PET/CT. 68 Ga-PSMA-11 PET/CT also uncovered 32 additional sites of metastasis in 25 patients not visible by standard imaging.

CONCLUSION

68 Ga-PSMA-11 PET/CT provides a definite disease stage in more than 90% of newly diagnosed patients with inconclusive standard imaging. Furthermore, it revealed additional sites of metastasis in 25 patients not detected by standard imaging.

Assessing the accuracy of [18F]PSMA-1007 PET/CT for primary staging of lymph node metastases in intermediate- and high-risk prostate cancer patients

Background

[¹⁸F]PSMA-1007 is a promising tracer for integrated positron emission tomography and computed tomography (PET/CT).

Objective

Our aim was to assess the diagnostic accuracy of [¹⁸F]PSMA-1007 PET/CT for primary staging of lymph node metastasis before robotic-assisted laparoscopy (RALP) with extended lymph node dissection (ePLND).

Design, Setting and Participants

The study was a retrospective cohort in a tertiary referral center. Men with prostate cancer that underwent surgical treatment for intermediate- or high-risk prostate cancer between May 2019 and August 2021 were included.

Interventions

[¹⁸F]PSMA-1007 PET/CT for initial staging followed by RALP and ePLND.

Outcome measurements and statistical analyses

Sensitivity and specificity were calculated both for the entire cohort and for patients with lymph node metastasis ≥ 3 mm. Positive (PPV) and negative (NPV) predictive values were calculated.

Results and limitations

Among 104 patients included in the analyses, 26 patients had lymph node metastasis based on pathology reporting and metastases were ≥ 3 mm in size in 13 of the cases (50%). In the entire cohort, the sensitivity and specificity of [¹⁸F]PSMA-1007 were 26.9% (95% confidence interval (CI); 11.6–47.8) and 96.2% (95% CI; 89.2–99.2), respectively. The sensitivity and specificity of [¹⁸F]PSMA-1007 to detect a lymph node metastasis ≥ 3 mm on PET/CT were 53.8% (95% CI; 25.1–80.8) and 96.7% (95% CI; 90.7–99.3), respectively. PPV was 70% and NPV 93.6%.

Conclusions

In primary staging of intermediate- and high-risk prostate cancer, [¹⁸F]PSMA-1007 PET/CT is highly specific for prediction of lymph node metastases, but the sensitivity for detection of metastases smaller than 3 mm is limited. Based on our results, [¹⁸F]PSMA-1007 PET/CT cannot completely replace ePLND.

Patient summary

This study investigated the use of an imaging method based on a prostate antigen-specific radiopharmaceutical tracer to detect lymph node prostate cancer metastasis. We found that it is unreliable to discover small metastasis.

Integrative Analysis of Bulk RNA-Seq and Single-Cell RNA-Seq Unveils the Characteristics of the Immune Microenvironment and Prognosis Signature in Prostate Cancer

The immune microenvironment is a culmination of the collaborative effort of immune cells and is important in cancer development. The underlying mechanisms of the tumor immune microenvironment in regulating prostate cancer (PRAD) are unclear. In the current study, 144 natural killer cell-related genes were identified using differential expression, single-sample gene set enrichment analysis, and weighted gene coexpression network analysis. Furthermore, VCL, ACTA2, MYL9, MYLK, MYH11, TPM1, ACTG2, TAGLN, and FLNC were selected as hub genes via the protein-protein interaction network. Based on the expression patterns of the hub genes, endothelial, epithelial, and tissue stem cells were identified as key cell subpopulations, which could regulate PRAD via immune response, extracellular signaling, and protein formation. Moreover, 27 genes were identified as prognostic signatures and used to construct the risk score model. Receiver operating characteristic curves revealed the good performance of the risk score model in both the training and testing datasets. Different chemotherapeutic responses were observed between the low- and high-risk groups. Additionally, a nomogram based on the risk score and other clinical features was established to predict the 1-, 3-, and 5-year progression-free interval of patients with PRAD. This study provides novel insights into the molecular mechanisms of the immune microenvironment and its role in the pathogenesis of PARD. The identification of key cell subpopulations has a potential therapeutic and prognostic use in PRAD.

Pelvic Lymph Node Dissection at Radical Prostatectomy for Intermediate Risk Prostate Cancer: Assessing Utility and Nodal Metastases Within a Statewide Quality Improvement Consortium

OBJECTIVE

To assess which patients with intermediate-risk PCa would benefit from a pelvic lymph node dissection (PLND) across the Michigan Urological Surgery Improvement Collaborative, given the discrepancy in recommendations. AUA guidelines for localized prostate cancer (PCa) state that PLND is indicated for patients with unfavorable intermediate-risk and high-risk PCa and can be considered in favorable intermediate-risk patients. NCCN guidelines recommend PLND when risk for nodal disease is ≥2%.

METHODS

Data regarding all robot-assisted radical prostatectomy (RARP) (March 2012-October 2020) were prospectively collected, including patient, and surgeon characteristics. Univariate and multivariate analyses of PLND rate and lymph node involvement (LN+) were performed.

RESULTS

Among 8,591 men undergoing RARP for intermediate-risk PCa, 80.2% were performed with PLND (n = 6883), of which 2.9% were LN+ (n = 198). According to the current AUA risk stratification system, 1.2% of favorable intermediate-risk PCa and 4.7% of unfavorable intermediate-risk PCa demonstrated LN+. There were also differences in the LN+ rates among the subgroups of favorable (0.0%-1.3%), and unfavorable (3.5%-5.0%) categories. Additional factors associated with higher LN+ rates include ≥50% cores positive, ≥35% involvement at any core, and unfavorable genomic classifier result, none of which contribute to the favorable/unfavorable subgroups.

CONCLUSION

These data support PLND at RARP for all patients with unfavorable intermediate-risk PCa. Our data also indicate patients with favorable intermediate-risk prostate cancer at greatest risk for LN+ are those with ≥50% cores positive, ≥35% involvement at any core, and/or unfavorable genomic classifier result.

The Added Value of 18F-FDG PET/CT Compared with 68Ga-PSMA PET/CT in Patients with Castration-Resistant Prostate Cancer

68Ga-prostate-specific membrane antigen (68Ga-PSMA) PET/CT is a commonly used imaging modality in prostate cancers. However, few studies have compared the diagnostic efficiency between 68Ga-PSMA and 18F-FDG PET/CT and evaluated whether a heterogeneous metabolic phenotype (especially 68Ga-PSMA-negative [-], 18F-FDG-positive [+] lesions) exists in patients with castration-resistant prostate cancer (CRPC). We determined the added value of 18F-FDG PET/CT compared with 68Ga-PSMA PET/CT in CRPC patients and identified CRPC patients who may benefit from additional 18F-FDG PET/CT. Methods: The data of 56 patients with CRPC who underwent both 68Ga-PSMA and 18F-FDG PET/CT from May 2018 to February 2021 were retrospectively analyzed. The patients were classified into 2 groups: with or without 68Ga-PSMA-, 18F-FDG+ lesions. The differences in patient characteristics between the 2 groups and predictors of patients who have at least 1 68Ga-PSMA-, 18F-FDG+ lesion were analyzed. Results: Although both the detection rate (75.0% vs. 51.8%, P = 0.004) and the number of positive lesions (135 vs. 95) were higher for 68Ga-PSMA PET/CT than for 18F-FDG PET/CT, there were still 13 of 56 (23.2%) patients with at least 1 68Ga-PSMA-, 18F-FDG+ lesion. Prostate-specific antigen (PSA) and the Gleason score were both higher in patients with 68Ga-PSMA-, 18F-FDG+ lesions than in those without (P = 0.04 and P < 0.001, respectively). Multivariate regression analysis showed that the Gleason score (≥8) and PSA (≥7.9 ng/mL) were associated with the detection rate of patients who had 68Ga-PSMA-, 18F-FDG+ lesions (P = 0.01 and P = 0.04, respectively). The incidences of having 68Ga-PSMA-, 18F-FDG+ lesions in low-probability (Gleason score < 8 and PSA < 7.9 ng/mL), medium-probability (Gleason score ≥ 8 and PSA < 7.9 ng/mL or Gleason score < 8 and PSA ≥ 7.9 ng/mL), and high-probability (Gleason score ≥ 8 and PSA ≥ 7.9 ng/mL) groups were 0%, 21.7%, and 61.5%, respectively (P < 0.001). Conclusion: Gleason score and PSA are significant predictors of 68Ga-PSMA-, 18F-FDG+ lesions, and CRPC patients with a high Gleason score and PSA may benefit from additional 18F-FDG PET/CT.

Recent Advancements in CT and MR Imaging of Prostate Cancer

CT and MRI are both commonly used in prostate cancer (PCa) management, which includes a large spectrum from screening positive pre-diagnosis phase to metastatic disease. CT and MRI have continually evolved to meet the changing demands for PCa management. For CT, novel techniques such as dual energy CT and photon counting CT show promising results for tissue characterization and quantification. For MRI, the detection, staging, and management of prostate cancer has been significantly improved by the development of multiparametric, biparametric, and whole-body MRI techniques. Additionally, research on ultrasmall superparamagnetic particles of iron oxide contrast-enhanced MRI has revealed promising results for nodal staging of PCa. In this manuscript we aim to outline the current status and recent advancements of CT and MRI in PCa imaging.

A Genomic-Clinicopathologic Nomogram for the Prediction of Lymph Node Invasion in Prostate Cancer

Background

Lymph node status is important for treatment decision making in prostate cancer (PCa). We aimed to develop a genomic-clinicopathologic nomogram for the prediction of lymph node invasion (LNI) in PCa.

Methods

Differentially expressed genes between LNI and non-LNI PCa samples were identified in the Cancer Genome Atlas database. Univariate Cox regression analysis and minimum redundancy maximum relevance were performed for gene selection. The synthetic minority oversampling technique (SMOTE) was conducted to balance the minority group (LNI group). Machine learning models were constructed in the training set and assessed in the validation set. Univariable logistic regression and multivariable logistic regression were applied to build a nomogram. Furthermore, the RNA-sequence data from our center were used to validate the expression levels of hub genes between five matched primary PCa and the corresponding LNI samples.

Results

The 37-gene-based support vector machine (SVM) model had the optimal synthesized performance in the SMOTE-balanced training (area under the curve (AUC): 0.947) and validation (AUC: 0.901) sets. Incorporating the SVM-based risk score and the Gleason grade, the genomic-clinicopathologic nomogram demonstrated good prediction and calibration both in the SMOTE-balanced training (AUC: 0.946) and validation (AUC: 0.910) sets. The dysregulated expression of hub genes between PCa and LNI samples was also validated.

Conclusion

The proposed nomogram combining the 37-gene-based SVM model with the Gleason grade had the potential to preoperatively predict LNI in PCa. Some of the hub genes should be prioritized for functional studies and mechanistic analyses.

Molecular Imaging of Newly Diagnosed Prostate Cancer

Positron emission tomography (PET) is a valuable imaging in evaluating many malignancies. There are various molecular imaging tracers that are currently being utilized with prostate cancer (PC). Several PET agents imaging different molecular processes in PC have reached the clinic. While all of these agents have demonstrated an advantage over conventional imaging, there are considerable differences in the performance of each in staging newly diagnosed PC. In this article, we review the current updates available of different PET tracers, with a strong focus on the emerging role of prostate-specific membrane antigen PET in the management of newly diagnosed PC.

The Heterogeneous Metabolic Patterns of Ganglia in 68Ga-PSMA, 11C-choline, and 18F-FDG PET/CT in Prostate Cancer Patients

PURPOSE

Studies have indicated that PSMA-positive ganglia represent a diagnostic pitfall for nuclear medicine physicians. No studies have described choline and FDG uptake in ganglia, which may be a source of misdiagnosis. Herein, we described the percentage and uptake pattern of 68Ga-PSMA, 11C-choline and 18F-FDG PET/CT in ganglia and evaluated the heterogeneous metabolic patterns of ganglia to differentiate from lymph node metastases (LNM).

METHODS

Thirty-nine patients who underwent 11C-choline PET/CT and 120 patients who underwent 68Ga-PSMA PET/CT and 18F-FDG PET/CT were retrospectively analyzed. The prevalence of PSMA-positive, choline-positive and FDG-positive ganglia was determined, the SUVmax of ganglia in different locations were measured, and the configuration was described. The SUVmax cutoff of PSMA-PET, choline-PET and FDG-PET was determined by ROC curve analysis to differentiate ganglia from LNM.

RESULTS

329 PSMA-positive ganglia were identified in 120 patients, 95 choline-positive ganglia were identified in 39 patients, and 39 FDG-positive ganglia were identified in 34 patients. PSMA-positive uptake was observed in 98.3%, 95.8%, and 80.0% of cervical, coeliac, and sacral ganglia, respectively. Choline-positive uptake was observed in 84.6%, 97.4%, and 61.5% of cervical, coeliac, and sacral ganglia, respectively. FDG-positive uptake was observed in 16.7%, 13.3%, and 2.5% of cervical, coeliac, and sacral ganglia, respectively. Cervical and coeliac ganglia had a higher rate of PSMA-positive uptake than sacral ganglia. Choline uptake was highest in coeliac ganglia followed by cervical and sacral ganglia. PSMA, choline or FDG uptake in LNM was all significantly higher than ganglia. ROC curve analysis revealed that at a 4.1 SUVmax cutoff of PSMA-PET, the sensitivity, specificity and accuracy of LNM identification was 88.4%, 97.9% and 96.2%, respectively. ROC curve analysis revealed that at a 2.35 SUVmax cutoff for choline-PET, the sensitivity, specificity, and accuracy of LNM identification was 95.0%, 92.6% and 93.0%, respectively. ROC curve analysis revealed that at a 2.55 SUVmax cutoff for FDG-PET, the sensitivity, specificity, and accuracy of LNM identification was 77.3%, 87.2%, and 81.9%, respectively. PSMA-, Choline- and FDG-positive ganglia are mainly band-shaped; most LNMs exhibited nodular and teardrop-shaped configuration.

CONCLUSION

68Ga-PSMA and 11C-choline uptake in ganglia was common, and FDG-positive ganglia were observed at lower frequency. Using 68Ga-PSMA, 11C-choline and 18F-FDG uptake and anatomic location and configuration, the differentiation of ganglia from adjacent LNM is feasible.

Use of 68Ga-PSMA-11 and 18F-FDG PET-CT Dual-Tracer to Differentiate Between Lymph Node Metastases and Ganglia

Purpose

Differentiating lymph node metastases (LNM) from peripheral ganglia by physiological prostate-specific membrane antigen (PSMA) uptake is challenging. Two tracers (⁶⁸Ga-PSMA-11 and ¹⁸F-fluorodeoxyglucose [FDG]) metabolic uptake patterns were evaluated by positron emission tomography-computed tomography (PET-CT), searching for differences that could tell ganglia from LNM.

Methods

Dual ⁶⁸Ga-PSMA-11 and ¹⁸F-FDG PET-CT data of 138 prostate cancer patients acquired from June 2018 to December 2019 were retrospectively evaluated. Ganglia and LNM with PSMA-11 uptake above local background were analyzed by the location and PSMA-11-PET and FDG-PET maximum standardized uptake value (SUVmax).

Results

PSMA-11-positive ganglia (n = 381) and LNM (n = 83) were identified in 138 and 58 patients, respectively. The LNM SUVmax of PSMA-11-PET (16.4 ± 14.8 vs 2.3 ± 0.7, P < 0.001) and FDG-PET (3.3 ± 3.2 vs 1.5 ± 0.5, P < 0.001) were higher than in ganglia. The probabilities of being an LNM in the low-potential (PSMA-11-PET SUVmax of <4.1 and FDG-PET SUVmax of <2.05), moderate-potential (PSMA-11-PET SUVmax of >4.1 and FDG-PET SUVmax of <2.05, or PSMA-11-PET SUVmax of <4.1 and FDG-PET SUVmax of >2.05), and high-potential (PSMA-11-PET SUVmax of >4.1 and FDG-PET SUVmax of >2.05) groups were 0.9% (3/334), 44.6% (37/83), and 91.5% (43/47), respectively (P < 0.001). The cervical and coeliac ganglia had higher PSMA-11 and FDG uptake than the sacral ganglia (P < 0.001 for all). LNM PSMA-11 and FDG uptake was similar in these three locations.

Conclusion

The FDG-PET and PSMA-11-PET SUVmax, especially when combined, could well differentiate LNM from ganglia. The tracers uptake differed between cervical/coeliac and sacral ganglia, so the lesion location should be considered during image assessment.

Diagnostic value of 18F-FDG PET/CT in patients with biochemical recurrent prostate cancer and negative 68Ga-PSMA PET/CT

PURPOSE

⁶⁸Ga-PSMA PET/CT has a high detection rate in prostate cancer patients with biochemical recurrence (BCR). However, few studies have reported other imaging methods for BCR with negative ⁶⁸Ga-PSMA PET/CT findings. We investigated the value of ¹⁸F-FDG compared with ⁶⁸Ga-PSMA and identified BCR patients with ⁶⁸Ga-PSMA-negative findings who are most likely to benefit from ¹⁸F-FDG PET/CT.

METHODS

Seventy-two BCR patients with negative ⁶⁸Ga-PSMA PET/CT findings were retrospectively identified from 510 patients who underwent concomitant ⁶⁸Ga-PSMA and ¹⁸F-FDG PET/CT between June 2018 and August 2020. Patients were categorised into groups with positive or negative ¹⁸F-FDG PET/CT findings. Differences in patients' characteristics between these two groups and predictors of positive ¹⁸F-FDG findings were analysed.

RESULTS

The detection rate of ¹⁸F-FDG PET/CT was 16.7% (12/72) in BCR patients with ⁶⁸Ga-PSMA-negative findings. PSA and Gleason score were significantly higher in the ¹⁸F-FDG-positive group than in the ¹⁸F-FDG-negative group (P < 0.001 and P < 0.001, respectively). A multivariate analysis indicated that PSA (PSA ≥2.3 ng/mL) and Gleason score (Gleason score ≥ 8) correlated with ¹⁸F-FDG-positive findings (P < 0.001 and P = 0.015, respectively). The probabilities of ¹⁸F-FDG-positive findings in the low-potential (PSA <2.3 ng/mL and Gleason score <8), moderate-potential (PSA <2.3 ng/mL and Gleason score ≥ 8 or PSA ≥2.3 ng/mL and Gleason score <8), and high-potential (PSA ≥2.3 ng/mL and Gleason score ≥ 8) groups were 0%, 11.5%, and 90.0%, respectively (P < 0.001).

CONCLUSION

PSA level and Gleason score are independent predictors of ¹⁸F-FDG-positive findings, and BCR patients with ⁶⁸Ga-PSMA-negative findings with high PSA and Gleason score are most likely to benefit from ¹⁸F-FDG PET/CT.

Prostate-specific Membrane Antigen Imaging in Clinical Guidelines: European Association of Urology, National Comprehensive Cancer Network, and Beyond

Prostate-specific membrane antigen (PSMA) imaging is characterized by superior accuracy compared to conventional imaging for identification of nodal and distant metastases in prostate cancer. The majority of international clinical guidelines recommend PSMA positron emission tomography/computed tomography for patients experiencing biochemical recurrence, even at low prostate-specific antigen values, to identify candidates for salvage therapies. However, its use in for primary staging is still not recommended.

Impact of 68 Gallium prostate-specific membrane antigen tracers on the management of patients with prostate cancer who experience biochemical recurrence

OBJECTIVE

To investigate the impact of ⁶⁸ Gallium prostate-specific membrane antigen (⁶⁸ Ga-PSMA) tracers on the management of prostate cancer (PCa) patients with biochemical recurrence (BCR) by conducting a systematical review and meta-analysis.

MATERIALS AND METHODS

We performed a literature search of the PubMed, Embase and Web of Science databases up to 29 October 2019. We included studies that reported the proportion of patients whose management changed after ⁶⁸ Ga-PSMA tracers were used in patients with BCR. We used the Quality Assessment of Diagnostic Accuracy Studies-2 tool to evaluate the quality of the included studies. The proportion of patients with management changes were pooled using a random-effects model. Subgroup analyses and meta-regression analyses were performed to explore the source of heterogeneity. A Sankey diagram was used to show treatment change from before to after the use of ⁶⁸ Ga-PSMA tracers.

RESULTS

We included 20 eligible studies (2026 patients). The pooled proportion of patients with management change was 53% (95% confidence interval [CI] 46-60) in patients with BCR and 51% (95% CI, 34-67) in patients with early BCR (prostate-specific antigen [PSA] <0.5 ng/mL). The pooled positron-emission tomography-positive rate in patients with BCR was 68% (95% CI 59-78). Fourteen studies reported management change, with most changes being intermodal in nature (42%, vs 17% intramodal change).

CONCLUSIONS

The use of ⁶⁸ Ga-PSMA tracers altered the management of more than half of PCa patients with BCR, including those with early BCR. ⁶⁸ Ga-PSMA tracers might be used to guide individualized treatment in patients with BCR, particularly those with early BCR.

Histological comparison between predictive value of preoperative 3-T multiparametric MRI and 68 Ga-PSMA PET/CT scan for pathological outcomes at radical prostatectomy and pelvic lymph node dissection for prostate cancer

OBJECTIVE

To evaluate the ability of preoperative multiparametric magnetic resonance imaging (mpMRI) and a gallium-68 prostate-specific membrane antigen positron emission tomography/computed tomography (⁶⁸ Ga-PSMA PET/CT) scan to predict pathological outcomes and also identify a group of men with a <5% risk of histological pelvic lymph node metastasis (LNM) at pelvic lymph node dissection (PLND) performed during a robot-assisted laparoscopic radical prostatectomy (RALP) for prostate cancer. We then aimed to compare these results to known risk calculators for LNM, including the Cancer of the Prostate Risk Assessment (CAPRA) score, Memorial Sloan Kettering Cancer Centre (MSKCC) and Briganti nomograms.

PATIENTS AND METHODS

Between July 2014 and September 2019 only men who had both a preoperative mpMRI and staging ⁶⁸ Ga-PSMA PET/CT at our institution followed by a RALP with PLND referred to a single specialist uropathology laboratory were considered for inclusion. The data were collected retrospectively prior to February 2019 and in a prospective manner thereafter. A model was built to allocate probabilities of the men with a negative ⁶⁸ Ga-PSMA PET/CT scan having a <5% risk of histologically LNM at RALP based on the preoperative radiological staging.

RESULTS

A total of 233 consecutive men met the inclusion criteria of which 58 men (24.9%) had a LNM identified on PLND histology. The median (range) International Society of Urological Pathology (ISUP) Grade was 5 (1-5) and the median (range) prostate-specific antigen level was 7.4 (1.5-72) ng/mL. The median (range) number of resected lymph nodes was 16 (1-53) and the median (range) number of positive nodes identified on histology was 2 (1-22). Seminal vesicle invasion on mpMRI was more common in node-positive men than in the absence of LNM (31% vs 12%). The maximum standardised uptake value of the primary tumour on ⁶⁸ Ga-PSMA PET/CT was higher in men with LNM (median 9.2 vs 7.2, P = 0.02). Suspected LNM were identified in 42/233 (18.0%) men with ⁶⁸ Ga-PSMA PET/CT compared with 22/233 (9.4%) men with mpMRI (P = 0.023). The positive and negative predictive value for ⁶⁸ Ga-PSMA PET/CT was 66.7% and 84.3% respectively, compared to 59.1% and 78.7% for mpMRI. A predictive model showed only two men (4.2%) with a negative preoperative ⁶⁸ Ga-PSMA PET/CT would be positive for a histological LNM if they are ISUP Grade < 5 and Prostate Imaging-Reporting and Data System (PI-RADS) <5; or ISUP Grade 5 with PI-RADS < 4. An inspection of three additional variables: CAPRA score, MSKCC and Briganti nomograms did not improve the predictive probability for this group. However, of the 61 men with ISUP Grade 4-5 malignancy and also a PI-RADS 5 mpMRI, 20 (32.8%) men had a microscopic LNM despite a negative preoperative ⁶⁸ Ga-PSMA PET/CT.

CONCLUSION

Preoperative ⁶⁸ Ga-PSMA/PET CT was more sensitive in identifying histological pelvic LNM than 3-T mpMRI. Men with a negative ⁶⁸ Ga-PSMA PET/CT have a lower risk of LNM than predicted with CAPRA scores or MSKCC and Briganti nomograms. We identified that the combination of a negative preoperative ⁶⁸ Ga-PSMA PET/CT, ISUP biopsy Grade <5 and PI-RADS <5 prostate mpMRI, or an ISUP Grade 5 with PI-RADS <4 on mpMRI was associated with a <5% risk of a LNM. The addition of CAPRA scores, MSKCC and Briganti nomograms did not improve the predictive probability within this model. Conversely, men with ISUP Grade 4-5 malignancy associated with a PI-RADS 5 prostate mpMRI had a >30% risk of microscopic LNM despite a negative preoperative ⁶⁸ Ga-PSMA PET/CT and this high-risk group would appear suitable for an extended PLND at the time of a radical prostatectomy.

Diagnostic Performance of 68Ga-PSMA-11 Positron-emission-tomography/Computed-tomography in a Large Cohort of Patients with Biochemical Recurrence of Prostate Carcinoma

Gallium-68 (Ga) prostate-specific-membrane-antigen positron-emission-tomography/computed-tomography is a highly promising method for imaging primary and recurrent prostate cancer. These dual-modality imaging technologies enable whole-body functional and anatomical evaluation in a single session. This study investigated the performance of Ga-prostate-specific-membrane-antigen-11 positron-emission-tomography/computed-tomography for detecting prostate carcinoma in patients with rising prostate-specific-antigen after primary therapy. Six hundred sixty (660) patients with biochemical recurrence referred for positron-emission-tomography/computed-tomography with Ga-prostate-specific-membrane-antigen-11 were evaluated retrospectively. Prostate-specific-antigen-stratified cohorts of pathological scan results were analyzed, and relationships between prostate-specific-antigen kinetics and PSMA-positive tumor lesions were correlated. Gallium-68 prostate-specific-membrane-antigen-11 positron-emission-tomography/computed-tomography showed a pathological prostate-specific-membrane-antigen uptake in 76% (500 of 660 patients). Positive scans were positively associated with prostate-specific-antigen (p<0.001). For patients with prostate-specific-antigen <0.2 ng mL, the PSMA-positive tumor lesions rate was 41%. Patients with prostate-specific-antigen of 0.2-<0.5 ng mL, 0.5-<1.0 ng mL, 1.0-<2.0 ng mL, and 2.0-<5.0 ng mL showed rates of 44.7%, 61.7%, 72.3%, 85.2%, respectively, and for prostate-specific-antigen of ≥5.0 ng mL it increased to 94%. Prostate-specific-antigen velocity was also correlated with PSMA-positive tumor lesions (p<0.001). In contrast, no association was found for prostate-specific-antigen doubling time (p=0.74). PSMA-positive tumor lesions were significantly increased in patients with primary intermediate- (Gleason Score7) and high-risk (Gleason Score>7) vs. low-risk prostate cancer (Gleason Score<7) (p<0.001). Our data confirm the high performance of Ga-prostate-specific-membrane-antigen positron-emission-tomography/computed-tomography for the detection of recurrent prostate cancer. This may alter treatment planning and has been documented in other studies as well.

Comparison of cross-sectional imaging techniques for the detection of prostate cancer lymph node metastasis: a critical review

Conventional staging for prostate cancer (PCa) is performed for men diagnosed with unfavorable-intermediate or higher risk disease. Computed tomography (CT) of the abdomen and pelvis and whole body bone scan remains the standard of care for the detection of visceral, nodal, and bone metastasis. The implementation of the 2012 United States Preventive Services Task Force recommendation against routine prostate specific antigen (PSA) screening resulted in a rise of metastatic PCa at the time of diagnosis, emphasizing the importance of effective imaging modalities for evaluating metastatic disease. CT plays a major role in clinical staging at the time of PCa diagnosis, but multi-parametric magnetic resonance imaging (MRI) is now integrated into many prostate biopsy protocols for the detection of primary PCa, and may be a surrogate for CT for nodal staging. Current guidelines incorporate both CT and MRI as appropriate cross-sectional imaging modalities for the identification of nodal metastasis in indicated patients. There is an ongoing debate about the utility of traditional cross-sectional imaging modalities as well as advanced imaging modalities in detection of both organ-confined PCa detection and nodal involvement.

Utility of index lesion volume assessed by multiparametric MRI combined with Gleason grade for assessment of lymph node involvement in patients with high-risk prostate cancer

PURPOSE

We examined the potential predictors of lymph node involvement and evaluated whether index lesion volume assessed using multiparametric magnetic resonance imaging is associated with lymph node involvement among patients with high-risk prostate cancer.

METHODS

Extended pelvic lymph node dissection was used to evaluate patients with lymph node involvement. We retrospectively analyzed consecutive 102 patients with high-risk prostate cancer who underwent extended pelvic lymph node dissection at our institution between 2011 and 2017. To evaluate the index lesion volume at multiparametric magnetic resonance imaging (mrV), lesions were manually contoured on each T2-weighted axial slice in combination with diffusion-weighted and dynamic contrast-enhanced magnetic resonance imaging and integrated using image analysis software. Logistic regression analysis was performed to identify predictors of lymph node involvement.

RESULTS

The median mrV was 1.4 ml (range 0-30.1 ml), and the median number of resected lymph nodes was 14 (range 7-38). Among 102 patients, 28 (28%) had lymph node involvement. Multivariate analysis identified significant predictors of lymph node involvement as follows: biopsy Gleason-grade group 5 (odds ratio = 17.2; 95% confidence interval, 2.1-299.0; P = 0.005), preoperative mrV (odds ratio = 1.14; 95% confidence interval, 1.02-1.30; P = 0.025) and percentage of positive cores with highest Gleason-grade group (odds ratio = 1.05; 95% confidence interval, 1.01-1.10; P = 0.005). Lymph node involvement was prevalent (69%) among tumors with Gleason-grade group 5 and mrV ≥3.4 ml, but was infrequently (10%) present among tumors with Gleason-grade group ≤4 and mrV <3.4 ml.

CONCLUSIONS

The combination of biopsy Gleason-grade and mrV may serve as a useful tool to stratify patients according to their risk of nodal metastases.

Prostate-specific membrane antigen PET-CT in patients with high-risk prostate cancer before curative-intent surgery or radiotherapy (proPSMA): a prospective, randomised, multicentre study

BACKGROUND

Conventional imaging using CT and bone scan has insufficient sensitivity when staging men with high-risk localised prostate cancer. We aimed to investigate whether novel imaging using prostate-specific membrane antigen (PSMA) PET-CT might improve accuracy and affect management.

METHODS

In this multicentre, two-arm, randomised study, we recruited men with biopsy-proven prostate cancer and high-risk features at ten hospitals in Australia. Patients were randomly assigned to conventional imaging with CT and bone scanning or gallium-68 PSMA-11 PET-CT. First-line imaging was done within 21 days following randomisation. Patients crossed over unless three or more distant metastases were identified. The primary outcome was accuracy of first-line imaging for identifying either pelvic nodal or distant-metastatic disease defined by the receiver-operating curve using a predefined reference-standard including histopathology, imaging, and biochemistry at 6-month follow-up. This trial is registered with the Australian New Zealand Clinical Trials Registry, ANZCTR12617000005358.

FINDINGS

From March 22, 2017 to Nov 02, 2018, 339 men were assessed for eligibility and 302 men were randomly assigned. 152 (50%) men were randomly assigned to conventional imaging and 150 (50%) to PSMA PET-CT. Of 295 (98%) men with follow-up, 87 (30%) had pelvic nodal or distant metastatic disease. PSMA PET-CT had a 27% (95% CI 23-31) greater accuracy than that of conventional imaging (92% [88-95] vs 65% [60-69]; p<0·0001). We found a lower sensitivity (38% [24-52] vs 85% [74-96]) and specificity (91% [85-97] vs 98% [95-100]) for conventional imaging compared with PSMA PET-CT. Subgroup analyses also showed the superiority of PSMA PET-CT (area under the curve of the receiver operating characteristic curve 91% vs 59% [32% absolute difference; 28-35] for patients with pelvic nodal metastases, and 95% vs 74% [22% absolute difference; 18-26] for patients with distant metastases). First-line conventional imaging conferred management change less frequently (23 [15%] men [10-22] vs 41 [28%] men [21-36]; p=0·008) and had more equivocal findings (23% [17-31] vs 7% [4-13]) than PSMA PET-CT did. Radiation exposure was 10·9 mSv (95% CI 9·8-12·0) higher for conventional imaging than for PSMA PET-CT (19·2 mSv vs 8·4 mSv; p<0·001). We found high reporter agreement for PSMA PET-CT (κ=0·87 for nodal and κ=0·88 for distant metastases). In patients who underwent second-line image, management change occurred in seven (5%) of 136 patients following conventional imaging, and in 39 (27%) of 146 following PSMA PET-CT.

INTERPRETATION

PSMA PET-CT is a suitable replacement for conventional imaging, providing superior accuracy, to the combined findings of CT and bone scanning.

FUNDING

Movember and Prostate Cancer Foundation of Australia. VIDEO ABSTRACT.

Eliminating microscopic lymph node metastasis by performing pelvic lymph node dissection during radical prostatectomy for prostate cancer

The oncological benefit of pelvic lymph node dissection (PLND) for prostate cancer (PCa) remains unclear. The therapeutic effect of PLND on the elimination of microscopic metastases during radical prostatectomy (RP) for PCa was examined in the current study. A total of 348 Japanese patients with high- or intermediate-risk PCa without lymph node metastasis, who underwent antegrade RP at the Kyushu Cancer Center (Fukuoka, Japan) between August 1998 and May 2013 were retrospectively analyzed. The patients were divided into the standard (obturator + internal iliac nodes) group and the expanded (standard + additional nodes) group according to the extent of PLND. Preoperative and postoperative characteristics were also analyzed to determine the factors associated with prostate-specific antigen (PSA) failure. Standard and expanded PLND were performed in 70.9% (247/348) and 29.1% (101/348) of cases, respectively. The results revealed that preoperative PSA levels were the only marked difference between the two groups. No differences were observed in the other preoperative and postoperative characteristics. Furthermore, the rate of PSA recurrence in each group did not differ to a statistically significant extent (P=0.3622). Reducing the area of dissection from expanded PLND to standard PLND significantly reduced the number of dissected lymph nodes (P<0.0001). Additionally, the PSA level, clinical tumor stage, Gleason score of the biopsy specimen, pathological tumor stage and extent of PLND were all associated with PSA recurrence, as determined via multivariate Cox hazards regression analysis (P=0.0177, P=0.0023, P=0.0027, P<0.0001 and P=0.0164, respectively). In high- and intermediate-risk patients without lymph node metastasis, a greater number of lymph nodes were dissected when the extent of dissection was greater. Furthermore, the extent of PLND was a significantly associated with PSA failure. The results indicated that PLND exerted a therapeutic effect by eliminating microscopic pelvic lymph node metastases that were not detected by routine pathological examinations.

Histologically Confirmed Diagnostic Efficacy of 18F-rhPSMA-7 PET for N-Staging of Patients with Primary High-Risk Prostate Cancer

¹⁸F-rhPSMA-7 (radiohybrid prostate-specific membrane antigen [PSMA]) is a novel ligand for PET imaging. Here, we present data from a retrospective analysis using PET/CT and PET/MRI examinations to investigate the efficacy of ¹⁸F-rhPSMA-7 PET for primary N-staging of patients with prostate cancer (PC) compared with morphologic imaging (CT or MRI) and validated by histopathology. Methods: Data from 58 patients with high-risk PC (according to the D'Amico criteria) who were staged with ¹⁸F-rhPSMA-7 PET/CT or PET/MRI at our institution between July 2017 and June 2018 were reviewed. The patients had a median prescan prostate-specific antigen value of 12.2 ng/mL (range, 1.2-81.6 ng/mL). The median injected activity of ¹⁸F-rhPSMA-7 was 327 MBq (range, 132-410 MBq), with a median uptake time of 79.5 min (range, 60-153 min). All patients underwent subsequent radical prostatectomy and extended pelvic lymph node dissection. The presence of lymph node metastases was determined by an experienced reader independently for both the PET and the morphologic datasets using a template-based analysis on a 5-point scale. Patient-level and template-based results were both compared with histopathologic findings. Results: Lymph node metastases were present in 18 patients (31.0%) and were located in 52 of 375 templates (13.9%). Receiver-operating-characteristic analyses showed ¹⁸F-rhPSMA-7 PET to perform significantly better than morphologic imaging on both patient-based and template-based analyses (areas under curve, 0.858 vs. 0.649 [P = 0.012] and 0.765 vs. 0.589 [P < 0.001], respectively). On patient-based analyses, the sensitivity, specificity, and accuracy of ¹⁸F-rhPSMA-7 PET were 72.2%, 92.5%, and 86.2%, respectively, and those of morphologic imaging were 50.0%, 72.5%, and 65.5%, respectively. On template-based analyses, the sensitivity, specificity, and accuracy of ¹⁸F-rhPSMA-7 PET were 53.8%, 96.9%, and 90.9%, respectively, and those of morphologic imaging were 9.6%, 95.0%, and 83.2%, respectively. Conclusion: ¹⁸F-rhPSMA-7 PET is superior to morphologic imaging for N-staging of high-risk primary PC. The efficacy of ¹⁸F-rhPSMA-7 is similar to published data for ⁶⁸Ga-PSMA-11.

The Role of Radical Prostatectomy and Lymph Node Dissection in Clinically Node Positive Patients

Patients diagnosed with clinically node-positive prostate cancer represent a population that has historically been thought to harbor systemic disease. Increasing evidence supports the role of local therapies in advanced disease, but few studies have focused on this particular population. In this review we discuss the limited role for conventional cross sectional imaging for accurate nodal staging and how molecular imaging, although early results are promising, is still far from widespread clinical utilization. To date, evidence regarding the role of radical prostatectomy and pelvic lymph node dissection in clinically node-positive disease comes from retrospective studies; overall surgery appears to be a reasonable option in selected patients, with improved oncological outcomes that could be attributed to both to its potential curative role in disease localized to the pelvis and to the improved staging to help guide subsequent multimodal treatment. The role of surgery in clinically node-positive disease needs higher-level evidence but meanwhile, radical prostatectomy with extended pelvic lymph-node dissection can be offered as a part of a multimodality approach with the patient.

Impact of 68Ga-PSMA-11 PET staging on clinical decision-making in patients with intermediate or high-risk prostate cancer

BACKGROUND

Accurate staging is of major importance to determine the optimal treatment modality for patients with prostate cancer. Positron emission tomography (PET) with prostate-specific membrane antigen (PSMA) is a promising technique that outperformed conventional imaging in the detection of nodal and distant metastases in previous studies. However, it is still unclear whether the superior sensitivity and specificity also translate into improved patient management. The aim of this study was to assess the performance of ⁶⁸Ga-PSMA-11 PET for staging of intermediate and high-risk prostate cancer and its potential impact on disease management.

METHODS

In this retrospective analysis, 116 patients who underwent ⁶⁸Ga-PSMA-11 PET/CT or MRI scans for staging of their intermediate or high-risk prostate cancer between April 2016 and May 2018 were included. The potential impact of ⁶⁸Ga-PSMA-11 PET staging on patient management was assessed within a simulated multidisciplinary tumour board where hypothetical treatment decisions based on clinical information and conventional imaging alone was determined. This treatment decision was compared with the treatment recommendation based on clinical information and ⁶⁸Ga-PSMA-11 PET imaging.

RESULTS

The primary tumour was positive on ⁶⁸Ga-PSMA-11 PET in 113 patients (97%). Nodal metastases were detected in 28 patients (24%) and bone metastases in 14 patients (12%). Compared with clinical staging and conventional imaging, ⁶⁸Ga-PSMA-11 PET resulted in new information in 42 of 116 patients (36%). In 32 of 116 patients (27%), this information would most likely have changed the management into a different therapy modality (15 patients, 13%) or adjusted treatment details (e.g. modification of radiotherapy field or lymph node dissection template; 17 patients, 14%).

CONCLUSION

Information from ⁶⁸Ga-PSMA-11 PET staging has the potential to change the management in more than a fourth of the patients who underwent PET staging for their intermediate to high-risk prostate cancer. Whether these more personalized ⁶⁸Ga-PSMA-11 PET-based treatment decisions will improve patient outcome needs further investigation.

Localising occult prostate cancer metastasis with advanced imaging techniques (LOCATE trial): a prospective cohort, observational diagnostic accuracy trial investigating whole-body magnetic resonance imaging in radio-recurrent prostate cancer

BACKGROUND

Accurate whole-body staging following biochemical relapse in prostate cancer is vital in determining the optimum disease management. Current imaging guidelines recommend various imaging platforms such as computed tomography (CT), Technetium 99 m (99mTc) bone scan and 18F-choline and recently 68Ga-PSMA positron emission tomography (PET) for the evaluation of the extent of disease. Such approach requires multiple hospital attendances and can be time and resource intensive. Recently, whole-body magnetic resonance imaging (WB-MRI) has been used in a single visit scanning session for several malignancies, including prostate cancer, with promising results, providing similar accuracy compared to the combined conventional imaging techniques. The LOCATE trial aims to investigate the application of WB-MRI for re-staging of patients with biochemical relapse (BCR) following external beam radiotherapy and brachytherapy in patients with prostate cancer.

METHODS/DESIGN

The LOCATE trial is a prospective cohort, multi-centre, non-randomised, diagnostic accuracy study comparing WB-MRI and conventional imaging. Eligible patients will undergo WB-MRI in addition to conventional imaging investigations at the time of BCR and will be asked to attend a second WB-MRI exam, 12-months following the initial scan. WB-MRI results will be compared to an enhanced reference standard comprising all the initial, follow-up imaging and non-imaging investigations. The diagnostic performance (sensitivity and specificity analysis) of WB-MRI for re-staging of BCR will be investigated against the enhanced reference standard on a per-patient basis. An economic analysis of WB-MRI compared to conventional imaging pathways will be performed to inform the cost-effectiveness of the WB-MRI imaging pathway. Additionally, an exploratory sub-study will be performed on blood samples and exosome-derived human epidermal growth factor receptor (HER) dimer measurements will be taken to investigate its significance in this cohort.

DISCUSSION

The LOCATE trial will compare WB-MRI versus the conventional imaging pathway including its cost-effectiveness, therefore informing the most accurate and efficient imaging pathway.

TRIAL REGISTRATION

LOCATE trial was registered on ClinicalTrial.gov on 18th of October 2016 with registration reference number NCT02935816.

Comparison between Zumsteg classification and Briganti nomogram for the risk of lymph-node invasion before radical prostatectomy

PURPOSE

To evaluate the performance of the Zumsteg classification to estimate the risk of lymph-node invasion (LNI) compared with the Briganti nomogram (BN) in prostatectomy patients with intermediate-risk prostate cancer (IRPC).

METHODS

We included consecutive patients who had extended pelvic lymph-node dissection associated with radical prostatectomy for IRPC. To be classified favorable intermediate risk (FIR), patients could only have one intermediate-risk factor, fewer than 50% positive biopsies and no primary Gleason score of 4.

RESULTS

On the 387 patients included, 149 (38.5%) and 238 (54.3%) were classified FIR and unfavorable intermediate risk (UIR), respectively, and 212 (54.8%) had a BN inferior to 5%. Thirty-eight patients (9.8%) had LNI: 6 FIR patients (4.0%) versus 32 UIR patients (13.4%) and 14 patients (6.6%) with a BN inferior to 5% versus 24 patients (13.7%) with a BN superior to 5%. Eight patients with a BN inferior to 5%, but classified UIR, had LNI. Sensitivity to detect LNI was higher with the Zumsteg classification than with the BN: 84.2% (CI 95% [68-93]) versus 63.2% (CI 95% [46-78]). Both screening tests were concordant to predict LNI (kappa coefficient of 0.076, p < 0.05 for Zumsteg and Briganti) CONCLUSIONS: Zumsteg classification appeared to be more sensitive and as effective (despite the impossibility to make decision curve analysis) than the BN to estimate the risk of LNI. Regarding the modest number of pN+ patients, further studies are needed to see the interest of proposing ePLND for UIR patients only.

68Ga-PSMA-11 PET has the potential to improve patient selection for extended pelvic lymph node dissection in intermediate to high-risk prostate cancer

INTRODUCTION

Radical prostatectomy with extended pelvic lymph node dissection (ePLND) is a curative treatment option for patients with clinically significant localised prostate cancer. The decision to perform an ePLND can be challenging because the overall incidence of lymph node metastasis is relatively low and ePLND is not free of complications. Using current clinical nomograms to identify patients with nodal involvement, approximately 75-85% of ePLNDs performed are negative. The aim of this study was to assess the added value of ⁶⁸Ga-PSMA-11 PET in predicting lymph node metastasis in men with intermediate- or high-risk prostate cancer.

METHODS

⁶⁸Ga-PSMA-11 PET scans of 60 patients undergoing radical prostatectomy with ePLND were reviewed for qualitative (visual) assessment of suspicious nodes and assessment of quantitative parameters of the primary tumour in the prostate (SUV_max, total activity (PSMA_total) and PSMA positive volume (PSMA_vol)). Ability of quantitative PET parameters to predict nodal metastasis was assessed with receiver operating characteristics (ROC) analysis. A multivariable logistic regression model combining PSA, Gleason score, visual nodal status on PET and primary tumour PSMA_total was built. Net benefit at each risk threshold was compared with five nomograms: MSKCC nomogram, Yale formula, Roach formula, Winter nomogram and Partin tables (2016).

RESULTS

Overall, pathology of ePLND specimens revealed 31 pelvic metastatic lymph nodes in 12 patients. ⁶⁸Ga-PSMA-11 PET visual analysis correctly detected suspicious nodes in 7 patients, yielding a sensitivity of 58% and a specificity of 98%. The area under the ROC curve for primary tumour SUV_max was 0.70, for PSMA_total 0.76 and for PSMA_vol 0.75. The optimal cut-off for nodal involvement was PSMA_total > 49.1. The PET model including PSA, Gleason score and quantitative PET parameters had a persistently higher net benefit compared with all clinical nomograms.

CONCLUSION

Our model combining PSA, Gleason score and visual lymph node analysis on ⁶⁸Ga-PSMA-11 PET with PSMA_total of the primary tumour showed a tendency to improve patient selection for ePLND over the currently used clinical nomograms. Although this result has to be validated, ⁶⁸Ga-PSMA-11 PET showed the potential to reduce unnecessary surgical procedures in patients with intermediate- or high-risk prostate cancer.

Association between Radical Prostatectomy and Survival in Men with Clinically Node-positive Prostate Cancer

Evidence supporting radical prostatectomy (RP) for men with clinically node-positive (cN+) prostate cancer (PC) is limited. In a US national database, we identified 741 men with cN+ nonmetastatic PC diagnosed during 2000-2015 who underwent definitive local therapy with RP (n=78), radiotherapy (RT) with neoadjuvant androgen deprivation therapy (ADT) (n=193), or nondefinitive therapy with ADT alone (n=445) or observation (n=25). We compared PC-specific mortality (PCSM) and all-cause mortality (ACM) using multivariable Fine-Gray competing risk regression and Cox regression, respectively. Compared to nondefinitive therapy, RP was associated with significantly better PCSM (subdistribution hazard ratio [SHR] 0.32, 95% confidence interval [CI] 0.16-0.66; p=0.002) and ACM (HR 0.36, 95% CI 0.21-0.61; p<0.001). Compared to RT, RP was not associated with a significant difference in PCSM (SHR 0.47, 95% CI 0.19-1.17; p=0.1) or ACM (HR 0.88, 95% CI 0.46-1.70; p=0.71). These data suggest that RP is associated with favorable survival outcomes that appear to be superior to those for patients who did not receive definitive therapy and comparable to those for patients receiving definitive ADT/RT. Randomized trials of surgery with multimodal therapy are needed. PATIENT SUMMARY: We found that in clinically node-positive prostate cancer, radical prostatectomy was associated with a cancer-specific and overall survival benefit compared to nondefinitive therapy. Randomized clinical trials are required to determine the best treatment approach in this patient population.

Diagnostic accuracy of F18 flucholine PET/CT for preoperative lymph node staging in newly diagnosed prostate cancer patients; a systematic review and meta-analysis

OBJECTIVES

The purpose of the current study was to investiagte the diagnostic accuracy of ^F18 flucholine (FCH) positron emission tomography/CT (PET/CT) for pre-operative lymph node (LN) staging in newly diagnosed prostate cancer (PCa) patients using meta-analysis.

METHODS

PubMed and Embase from the earliest available date of indexing through December 31, 2018, were searched for studies evaluating the diagnostic performance of ^F18 FCH PET/CT for preoperative LN staging in newly diagnosed PCa. We determined the sensitivities and specificities across studies, calculated positive and negative likelihood ratios (LR + and LR-), and constructed summary receiver operating characteristic curves.

RESULTS

Across seven studies (627 patients), the pooled sensitivity was 0.57 [95% confidence interval (CI) (0.42-0.70)] and a pooled specificity of 0.94 [95% CI (0.89-0.97)]. Likelihood ratio (LR) syntheses gave an overall positive likelihood ratio (LR+) of 10.2 (95% CI; 5.0-21.0) and negative likelihood ratio (LR-) of 0.46 (95% CI; 0.33-0.64). The pooled diagnostic odds ratio was 22 (95% CI; 9-54).

CONCLUSIONS

^F18 FCH PET/CT shows a low sensitivity and high specificity for the detection of metastatic LNs in patients with newly diagnosed PCa. Also, ^F18 FCH PET/CT is only useful for confirmation of LN metastasis (when positive) in PCa patients.

ADVANCES IN KNOWLEDGE

^F18 FCH PET/CT demonstrates low sensitivity but high specificity for diagnosis of metastatic LNs in patients with newly diagnosed PCa. Also, ^F18 FCH PET/CT is only useful for confirmation of LN metastasis (when positive) in PCa patients.

68Ga-PSMA-11 PET/CT in newly diagnosed prostate cancer: diagnostic sensitivity and interobserver agreement

PURPOSE

To determine the diagnostic sensitivity and interobserver agreement of Gallium 68-prostate-specific membrane antigen positron emission tomography/computed tomography (⁶⁸Ga-PSMA-11 PET/CT) imaging for diagnosis and staging of patients with newly diagnosed prostate cancer (PC).

MATERIALS AND METHODS

One hundred and seventy-three men (mean age, 68 ± 7.7 years; range 46-84 years) with newly diagnosed, untreated PC were enrolled in this prospective study between January 2017 and August 2018. All patients underwent a ⁶⁸Ga-PSMA-11 PET/CT examination. For each patient, we determined the disease stage, the Gleason score, and the maximum standardized uptake value (SUVmax) for primary prostatic tumor and extraprostatic metastases. The diagnostic sensitivity and interobserver agreement of ⁶⁸Ga-PSMA-11 PET/CT for diagnosis and staging of PC were established by histopathology as the reference standard.

RESULTS

⁶⁸Ga-PSMA-11 PET/CT examinations were interpreted as positive for PC in 166 of 173 patients (101 patients had primary prostatic tumor only, two patients had extraprostatic metastases only and 63 patients had combined lesions). The sensitivity of ⁶⁸Ga-PSMA-11 PET/CT examination in the diagnosis of PC was 96%. ⁶⁸Ga-PSMA-11 PET/CT produced a significant change of stage in 28.6% patients with an upstage in 17.9% patients and a downstage in 10.7% patients. The interobserver agreements were almost good to perfect (k = 0.63-0.89) for visual image interpretation, SUVmax measurement, and tumor staging.

CONCLUSION

⁶⁸Ga-PSMA-11 PET/CT is a valuable tool with high diagnostic sensitivity (96%) and high reproducibility for diagnosis and staging of patients with newly diagnosed PC.

Matched-Pair Comparison of 68Ga-PSMA-11 PET/CT and 18F-PSMA-1007 PET/CT: Frequency of Pitfalls and Detection Efficacy in Biochemical Recurrence After Radical Prostatectomy

¹⁸F-labeled prostate-specific membrane antigen (PSMA)-ligand PET has several principal advantages over ⁶⁸Ga-PSMA-11. The purpose of this retrospective study was to evaluate the frequency of non-tumor-related uptake and the detection efficacy comparing ⁶⁸Ga-PSMA-11 PET/CT and ¹⁸F-PSMA-1007 PET/CT in recurrent prostate cancer (PC) patients. Methods: The study included 102 patients with biochemically recurrent PC after radical prostatectomy undergoing ¹⁸F-PSMA-1007 PET/CT imaging. On the basis of various clinical variables, patients with corresponding ⁶⁸Ga-PSMA-11 PET/CT scans were matched. All PET/CT scans (n = 204) were reviewed by 1 nuclear medicine physician. First, all PET-positive lesions were noted. Then, lesions suspected of being recurrent PC were differentiated from lesions attributed to a benign origin on the basis of known pitfalls and information from CT. For each region, the SUV_max of the lesion with the highest PSMA-ligand uptake was noted. Detection rates were determined, and SUV_max was compared separately for ⁶⁸Ga-PSMA-11 and ¹⁸F-PSMA-1007. Results: In total, ¹⁸F-PSMA-1007 PET and ⁶⁸Ga-PSMA-11 PET revealed 369 and 178 PSMA-ligand-positive lesions, respectively. ¹⁸F-PSMA-1007 PET revealed approximately 5 times more lesions attributed to a benign origin than did ⁶⁸Ga-PSMA-11 PET (245 vs. 52 lesions, respectively). The benign lesions most frequently observed were ganglia, unspecific lymph node, and bone lesions, at a rate of 43%, 31%, and 24% for ¹⁸F-PSMA-1007 PET and 29%, 42%, and 27% for ⁶⁸Ga-PSMA-11 PET, respectively. The SUV_max of lesions attributed to a benign origin was significantly higher (P < 0.0001) for ¹⁸F-PSMA-1007 PET. Further, a similar number of lesions was attributed to recurrent PC (124/369 for ¹⁸F-PSMA-1007 PET and 126/178 for ⁶⁸Ga-PSMA-11 PET). Conclusion: The number of lesions with increased PSMA-ligand uptake attributed to a benign origin is considerably higher for ¹⁸F-PSMA-1007 PET than for ⁶⁸Ga-PSMA-11 PET. This finding indicates the need for sophisticated reader training emphasizing known pitfalls and reporting within the clinical context.

Comparing the Staging/Restaging Performance of 68Ga-Labeled Prostate-Specific Membrane Antigen and 18F-Choline PET/CT in Prostate Cancer: A Systematic Review and Meta-analysis

PURPOSE

PET/CT using prostate-specific membrane antigen (PSMA) and choline radiotracers is widely used for diagnosis of prostate cancer. However, the roles of and differences in diagnostic performance between these 2 radiotracers for prostate cancer are unclear. The aim of this study was to compare the staging and restaging performance of Ga-labeled PSMA and F-choline PET/CT imaging in prostate cancer.

METHODS

A comprehensive search was performed in PubMed for studies reporting the staging performance of Ga-PSMA and F-choline PET/CT in prostate cancer from the inception of the database to October 1, 2018, according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement. Thirty-five studies were included in this systematic review and meta-analysis. Pooled estimates of patient- and lesion-based sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) for Ga-PSMA and F-choline PET/CT were calculated alongside 95% confidence intervals. Summary receiver operating characteristic curves were plotted, and the area under the summary receiver operating characteristic curve (AUC) was determined alongside the Q* index.

RESULTS

The patient-based overall pooled sensitivity, specificity, PLR, NLR, DOR, and AUC of Ga-PSMA PET/CT for staging in prostate cancer (13 studies) were 0.92, 0.94, 7.91, 0.14, 79.04, and 0.96, respectively, whereas those of F-choline PET/CT (16 studies) were 0.93, 0.83, 4.98, 0.10, 68.27, and 0.95. The lesion-based overall pooled sensitivity, specificity, PLR, NLR, DOR, and AUC of Ga-PSMA PET/CT for staging in prostate cancer (9 studies) were 0.83, 0.95, 23.30, 0.17, 153.58, and 0.94, respectively, and those of F-choline PET/CT (4 studies) were 0.81, 0.92, 8.59, 0.20, 44.82, and 0.98. In both patient- and lesion-based imaging, there was no statistically significant difference in the abilities of detecting or excluding prostate cancer between Ga-PSMA PET/CT and F-choline PET/CT.

CONCLUSIONS

For staging and restaging performance in patients with prostate cancer, there was no significant difference between Ga-PSMA PET/CT and F-choline PET/CT. Ga-PSMA PET/CT and F-choline PET/CT have demonstrated high diagnostic performance for accurate staging and restaging in patients with prostate cancer, and thus both should be considered for staging in this disease.

Evolution of definitive external beam radiation therapy in the treatment of prostate cancer

PURPOSE

Although the clinical significance of a diagnosis of prostate cancer for some men is debated, for many men it leads to significant morbidity and mortality. Radical treatment of clinically localized prostate cancer has been shown to improve survival in men with intermediate or high-risk disease. There is no high level evidence to support the superiority of radical prostatectomy, with or without adjuvant or salvage external beam radiotherapy in comparison to definitive radiotherapy with or without androgen deprivation, and the choice should be individualized. External beam radiation therapy practices are in constant evolution, and numerous strategies have been investigated to improve either efficacy or reduce toxicity, or both.

METHODS

Randomized controlled trials investigating strategies to improve efficacy, reduce toxicity, or both of external beam radiotherapy have been reviewed in men with prostate cancer without nodal or distant metastases. These strategies include the use of neo-adjuvant and adjuvant androgen deprivation, dose-escalation, hypofractionation, whole pelvic radiation therapy, incorporation of improved imaging, image- guided radiation therapy, and adjuvant systemic therapy. The evidence to date for these strategies is discussed, noting limitations in applying the results of reported trials to men treated in contemporary settings.

RESULTS

A number of strategies have shown improvements in biochemical control using external beam radiotherapy. To date, only with the use of androgen deprivation therapy has this translated into improvements in disease specific and overall survival. This may reflect the long natural history of prostate cancer and high incidence of competing risks. Technological advances have enabled dose escalation with reduced toxicity, of paramount importance given the long natural history.

RESULTS

The use of external beam radiation therapy in prostate cancer is evolving with numerous strategies incorporated to improve outcomes. The optimum dose and fractionation and use of androgen deprivation or systemic adjuvants for each man is unclear based on current evidence and prognostic and predictive parameters. Patient preferences play an important role in chosen therapy. It is hoped that future studies better capture all prostate cancer- and treatment- related morbidity to clarify the optimal therapy choices for each man with prostate cancer.