Can Negative Prostate-specific Membrane Antigen Positron Emission Tomography/Computed Tomography Avoid the Need for Pelvic Lymph Node Dissection in Newly Diagnosed Prostate Cancer Patients? A Systematic Review and Meta-analysis with Backup Histology as Reference Standard

Abstract

Context: The role of positron emission tomography/computed tomography (PET/CT) with prostate-specific membrane antigen (PSMA) in the primary staging for patients with prostate cancer (PCa) is still debated.

Objective: To analyze published studies reporting the accuracy of PSMA PET/CT for detecting lymph node invasion (LNI) at pelvic lymph node dissection (PLND).

Evidence acquisition: A search of PubMed/MEDLINE, Cochrane library's Central, EMBASE and Scopus databases, from inception to May 2021, was conducted. The primary outcome was to evaluate the sensitivity, specificity, positive (PPV) and negative (NPV) predictive values of PSMA PET/CT in detecting LNI on a per-patient level. As a secondary outcome, NPV of PET PSMA was tested on a per-node-level analysis. Detection rates were pooled using random-effect models. Preplanned subgroup analyses tested the diagnostic accuracy after stratification for the preoperative risk group. PPV and NPV variation over LNI prevalence was evaluated. Only studies including extended PLND (ePLND) as the reference standard test were included.

Evidence synthesis: Twenty-seven studies, with a total of 2832 participants, were included in quantitative synthesis. The sensitivity, specificity, PPV, and NPV of PSMA PET/CT for LNI were, respectively, 58% (95% confidence interval [CI] 50-66%), 95% (95% CI 93-97%), 79% (95% CI 72-85%), and 87% (95% CI 84-89%), with overall moderate heterogeneity between studies. At bivariate analysis, the diagnostic accuracy of PSMA PET/CT estimated through summary receiver operating characteristic-derived area under the curve was 84% (95% CI 81-87%). On a per-node level, NPV of PET PSMA was 97% (95% CI 96-99%). At subgroup analyses, according to preoperative risk groups, sensitivity, specificity, PPV, and NPV were 51%, 93%, 73%, and 81%, respectively, in high-risk patients. Over the LNI prevalence range of 5-40%, PPV increased from 59% to 91%, while NPV decreased from 99% to 84%.

Conclusions: PSMA PET/CT scan provides promising accuracy in the field of primary nodal staging for PCa. The high NPV in men with a lower risk of LNI might be clinically useful to reduce the number of unnecessary PLND procedures performed. Conversely, in high-risk patients, negative PSMA PET/CT cannot replace staging ePLND.

Patient summary: In this systematic review and meta-analysis, we demonstrated that prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) scan may optimize the primary nodal staging and surgical management of prostate cancer patients candidate to radical prostatectomy. The high negative predictive value in men with a lower risk of lymph node invasion might be clinically useful for reducing the number of useless pelvic lymph node dissection (PLND) procedures performed. Conversely, in high-risk patients, negative PSMA PET/CT cannot allow avoiding of PLND.

Keywords: Diagnostic accuracy; Negative predictive value; Positive predictive value; Positron emission tomography; Prostate cancer; Prostate-specific membrane antigen.