How accurate is 68Gallium-prostate specific membrane antigen positron emission tomography / computed tomography (68Ga-PSMA PET/CT) on primary lymph node staging before radical prostatectomy in intermediate and high risk prostate cancer? A study of patient- and lymph node- based analyses

Robot-Assisted Radical Prostatectomy: Concordance and Correlation Between Preoperative Positron Emission Tomography-Computed Tomography With Prostate-Specific Membrane Antigen (PET-CT PSMA) and Final Histopathological Report

BACKGROUND

Positron emission tomography-computed tomography with prostate-specific membrane antigen (PET-CT PSMA) has revolutionized the preoperative staging of prostate cancer, particularly for assessing seminal vesicle and lymph node invasion. However, its correlation and agreement with definitive histopathology remain unclear.

OBJECTIVE

The study aimed to evaluate the diagnostic performance, correlation, and agreement between PET-CT PSMA and final histopathological findings for seminal vesicle and lymph node invasion in patients undergoing robot-assisted radical prostatectomy.

METHODS

This retrospective, single-center study included 194 patients who underwent PET-CT PSMA and radical prostatectomy. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy were calculated. Correlation (Spearman's rho) and agreement (kappa coefficient) between PET-CT PSMA and final histopathology were analyzed.

RESULTS

Seminal vesicle invasion was detected in 11.9% of cases by histopathology and 12.4% by PET-CT PSMA, while lymph node invasion was reported in 4.8% and 10.3%, respectively. PET-CT PSMA exhibited high specificity (91.23% for seminal vesicles, 92% for lymph nodes) and high NPVs (91.76% and 96.84%, respectively), but low sensitivity (39.13% and 40%) and low PPV for lymph nodes (20%). Correlation between PET-CT PSMA and histopathology was low for seminal vesicle invasion (rho = 0.298; p = 0.0001) and lymph node invasion (rho = 0.232; p = 0.017). Agreement was also poor for seminal vesicle invasion (kappa = 0.298) and lymph node invasion (kappa = 0.217).

CONCLUSION

PET-CT PSMA demonstrates high specificity and NPV but low sensitivity, correlation, and agreement with final histopathology. While useful for ruling out disease, its positive findings should be interpreted with caution.

A Comprehensive Systematic Review and Meta-analysis of the Role of Prostate-specific Membrane Antigen Positron Emission Tomography for Prostate Cancer Diagnosis and Primary Staging before Definitive Treatment

BACKGROUND AND OBJECTIVE

Positron emission tomography (PET) with prostate-specific membrane antigen (PSMA) in the diagnosis and primary staging of patients with prostate cancer (PCa) has an established role, but recent summative evidence on its actual diagnostic and staging value is still missing. We aimed to collect and analyze published studies reporting the accuracy of PSMA PET for the diagnosis of clinically significant prostate cancer (csPCa) and detection of distant metastases at primary staging before definitive treatment.

METHODS

We performed a systematic review of the literature, by searching the PubMed/MEDLINE, Cochrane library's CENTRAL, EMBASE, and Scopus databases, from inception to April 2024. Two coprimary outcomes were assessed: first, to evaluate the sensitivity, specificity, positive (PPV) and negative (NPV) predictive values of PSMA PET in detecting intraprostatic csPCa on a per-patient level, and second, to assess the positivity rates of metastatic disease in the primary staging, prior to definitive therapy. As a secondary outcome, the diagnostic accuracy of PET PSMA for the detection of lymph nodal invasion (LNI) was tested in a per-patient-level analysis of studies where pelvic lymph node dissection (PLND) was available as the reference standard. Positivity and detection rates were pooled using random-effect models. Preplanned subgroup analyses tested the diagnostic accuracy of PET PSMA across different study cohorts. Variation in PPV and NPV over csPCa and LNI prevalence was evaluated.

KEY FINDINGS AND LIMITATIONS

In total, 12 and 99 studies, with a total of 1533 and 18 649 participants, respectively, were included in the quantitative synthesis for intraprostatic diagnosis and staging. For intraprostatic disease, the sensitivity, specificity, PPV, and NPV of PSMA PET for csPCa were 82% (95% confidence interval [CI] 73-90%), 67% (95% CI 46-85%), 77% (95% CI 63-88%), and 73% (95% CI 56-87%), respectively. At a bivariate analysis, the diagnostic accuracy of PSMA PET estimated through a summary receiver operating characteristic curve-derived area under the curve was 84%, increasing up to 88% when combined with magnetic resonance imaging (MRI). On staging level, PSMA PET results were positive outside the prostate in 23% of the patients, with substantial variation in positivity rates between high-risk (31%) and intermediate-risk (12%) subcohorts. When using PLND as the reference standard (51 studies, 7713 patients), the sensitivity, specificity, PPV, and NPV of PSMA PET were, respectively, 54%, 94%, 77%, and 86%. With higher csPCa and LNI prevalence, a similar increase in PPV and a decrease in NPV were observed.

CONCLUSIONS AND CLINICAL IMPLICATIONS

The current updated systematic review and meta-analysis provides updated evidence on the diagnostic and staging accuracy of PSMA PET in PCa. We reported good accuracy of PSMA PET to discriminate csPCa, particularly when added to MRI, but NPV alone is insufficient to omit a biopsy. Regarding staging, PSMA PET cannot be used alone to determine the need for lymph node dissection (LND) and should be combined with additional clinical information within predictive tools. As such, further research should develop and validate models that incorporate PSMA PET to reliably inform biopsy or LND.

A systematic review and meta-analysis to evaluate the diagnostic accuracy of PSMA PET/CT in the initial staging of prostate cancer

BACKGROUND

Positron Emission Tomography-Computed Tomography using Prostate-Specific Membrane Antigen (PSMA PET/CT) is notable for its superior sensitivity and specificity in detecting recurrent PCa and is under investigation for its potential in pre-treatment staging. Despite its established efficacy in nodal and metastasis staging in trial setting, its role in primary staging awaits fuller validation due to limited evidence on oncologic outcomes. This systematic review and meta-analysis aims to appraise the diagnostic accuracy of PSMA PET/CT compared to CI for comprehensive PCa staging.

METHODS

Medline, Scopus and Web of science databases were searched till March 2023. Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines were followed to identify eligible studies. Primary outcomes were specificity, sensitivity, positive predictive value (PPV) and negative predictive value (NPV) of PSMA PET/CT for local, nodal and metastatic staging in PCa patients. Due to the unavailability of data, a meta-analysis was feasible only for detection of seminal vesicles invasion (SVI) and LNI.

RESULTS

A total of 49 studies, comprising 3876 patients, were included. Of these, 6 investigated accuracy of PSMA PET/CT in detection of SVI. Pooled sensitivity, specificity, PPV and NPV were 42.29% (95%CI: 29.85-55.78%), 87.59% (95%CI: 77.10%-93.67%), 93.39% (95%CI: 74.95%-98.52%) and 86.60% (95%CI: 58.83%-96.69%), respectively. Heterogeneity analysis revealed significant variability for PPV and NPV. 18 studies investigated PSMA PET/CT accuracy in detection of LNI. Aggregate sensitivity, specificity, PPV and NPV were 43.63% (95%CI: 34.19-53.56%), 85.55% (95%CI: 75.95%-91.74%), 67.47% (95%CI: 52.42%-79.6%) and 83.61% (95%CI: 79.19%-87.24%). No significant heterogeneity was found between studies.

CONCLUSIONS

The present systematic review and meta-analysis highlights PSMA PET-CT effectiveness in detecting SVI and its good accuracy in LNI compared to CI. Nonetheless, it also reveals a lack of high-quality research on its performance in clinical T staging, extraprostatic extension and distant metastasis evaluation, emphasizing the need for further rigorous studies.

Survival outcomes of patients treated with local therapy for nonmetastatic prostate cancer with high prostate-specific antigen concentrations

BACKGROUND

Patients with nonmetastatic prostate cancer (nmPCa) and high prostate-specific antigen (PSA) levels due to the high likelihood of metastasis pose a clinical dilemma regarding their optimal treatment and long-term outcomes after initial local therapy. We aimed to evaluate the oncologic outcomes of patients treated with radical prostatectomy (RP) or radiotherapy (RT) for nmPCa with high PSA levels.

METHODS

We queried the Surveillance, Epidemiology, and End Results (SEER) database to identify patients diagnosed with nmPCa who received RP or RT from 2004 through 2015. We included nmPCa patients with high PSA levels categorized as ≥50 and ≥98 ng/mL, the highest level recorded in SEER. We used the Kaplan-Meier method and Cox proportional hazards to analyze cancer-specific (CSS) and overall survival (OS).

RESULTS

We included 6177 patients with nmPCa and PSA ≥ 50 ng/mL at diagnosis; 1698 (27%) had PSA ≥ 98 ng/mL. Of these, 1658 (26.8%) underwent RP and 4519 (73.16%) patients received primary RT. Within a median of 113 months (interquartile range 74-150 months), the 5- and 10-year CSS estimates were 92.3% and 81.5% respectively; 10-year OS was 61%. In the PSA ≥ 98 ng/mL subgroup 5- and 10-year CSS estimates were 89.2% and 76%, respectively. In multivariable analyses for CSS, ISUP grade group (p < 0.001), N stage (p < 0.001), treatment with RP (hazard ratio [HR] = 0.60, 95% confidence interval [CI] 0.43-0.83, p < 0.001), and patient's age (p < 0.05) were associated with improved CSS. In the whole cohort of patients with PSA ≥ 50 ng/mL and RP subgroup, PSA failed to retain its independent prognostic value for CSS.

CONCLUSIONS

Patients treated with local therapy for nmPCa with very high PSA at diagnosis have relatively good long-term oncological outcomes. Therefore, among well-selected patients with nmPCa, high PSA levels alone should not preclude the use of radical local therapy. Potential selection bias limits inferences about the relative effectiveness of specific local therapies 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.

Head-to-Head Comparison of 68Ga-PSMA-11 PET/CT and Multiparametric MRI for Pelvic Lymph Node Staging Prior to Radical Prostatectomy in Patients With Intermediate to High-Risk Prostate Cancer: A Meta-Analysis

PURPOSE

To compare the diagnostic performance of 68Ga-PSMA-11 PET/CT and mpMRI for pelvic lymph node staging prior to radical prostatectomy in prostate cancer (PCa) patients based on per patient data.

METHODS

PubMed and Embase databases were searched until October 2020 for eligible studies evaluating head-to-head comparison of 68Ga-PSMA-PET/CT and mpMRI for the detection of pelvic lymph node metastases (PLNMs) using pelvic lymph node dissection (PLND) as gold standard. The pooled sensitivity, specificity, and area under the summary receiver-operating characteristics curve (AUC) were determined for the two imaging modalities.

RESULTS

Nine studies with 640 patients were included. The pooled sensitivity, specificity, and AUC for 68Ga-PSMA-11 PET/CT vs. mpMRI were 0.71 (95% CI: 0.48-0.86) vs. 0.40 (95% CI: 0.16-0.71), 0.92 (95% CI: 0.88-0.95) vs. 0.92 (95% CI: 0.80-0.97), and 0.92 (95% CI: 0.88-0.95) vs. 0.82 (95% CI: 0.79-0.86), respectively. There was substantial heterogeneity for both imaging modalities, and meta-regression analysis revealed that the number of patients, prevalence of PLNMs, PSA level, reference standard, and risk classification might be the potential causes of heterogeneity.

CONCLUSION

This meta-analysis of head-to-head comparison studies confirms that there is a trend toward a higher sensitivity and diagnostic accuracy of 68Ga-PSMA-11 PET/CT compared to mpMRI for the detection of PLNMs in PCa patients. Nevertheless, according to current guidelines, PLND still needs to be recommended in case of negative results from 68Ga-PSMA-11 PET/CT due to significant risk of malignancy.