Accuracy of 68Ga-PSMA PET-CT and PET-MRI in lymph node staging for localized prostate cancer

Abstract

Objective: To evaluate the predictive value of positron emission computed tomography or magnetic resonance (PET-CT and PET-MRI) using gallium-68-labeled prostate-specific membrane antigen ( 68 Ga-PSMA) in lymph node involvement in prostate cancer. Methods: A retrospective study comprising 91 patients diagnosed with prostate cancer between 2016 to 2020, who underwent 68 Ga-PSMA PET-CT or PET-MRI for staging before prostatectomy. The patients were divided into Group 1, with 65 patients with satisfactory pathological lymph node analysis, and Group 2, with 91 patients representing the sum of patients with pathological lymph node analysis and those with postoperative prostate-specific antigen within 60 days after surgery. Receiver Operating Characteristic curves were used to assess accuracy of predictive capacity of imaging exams for lymph node involvement. Results: Regarding local clinical staging, the groups showed similar results, and 50% were classified as staging T2a. The accuracy of 68 Ga-PSMA PET-CT for prostate cancer lymph node staging was 86.5% (95%CI 0.74-0.94; p=0.06), with a sensitivity of 58.3% and specificity of 95%. The accuracy of 68 Ga-PSMA PET-MRI was 84.6% (95%CI 0.69-0.94; p=0.09), with a sensitivity of 40% and specificity of 100%. Considering both 68 Ga-PSMA PET-CT and PET-MRI, the accuracy was 85.7% (95%CI 0.76-0.92; p=0.015), with sensitivity of 50% and specificity of 97%. Conclusion: The imaging tests 68 Ga-PSMA PET-CT and PET-MRI were highly accurate to detect preoperative lymph node involvement, and could be useful tools to indicate the need for extended lymph node dissection during radical prostatectomy.

Evaluating the Correlation between Serum Prostate-specific antigen Values and Gleason Score of the Prostate Carcinoma with Gallium 68- Prostate-specific membrane antigen Uptake in the Prostate Tumor in Primary Staging

“…In another study by Kubilay et (19). Two recent retrospective studies and a literature review reached the same conclusion regarding the utility of Ga-68-PSMA-PET/CT scan in detecting lymph node metastases of prostate tumors (20)(21)(22).…”

Evaluating the Correlation Between Serum PSA Values and Gleason Score of the Prostate Carcinoma with Ga68-PSMA Uptake in the Prostate Tumor in Primary Staging

“…The authors also concluded that Ga-68-PSMA-PET/CT scan had high speci city and accuracy for detecting lymph node metastasis (96.5% and 84.5%, respectively), but its sensitivity was relatively low (30.6%) (19). Two recent retrospective studies and a literature review reached the same conclusion regarding the utility of Ga-68-PSMA-PET/CT scan in detecting lymph node metastases of prostate tumors (20)(21)(22).…”

Editorial Comment

“…While there are significant diagnostic and therapeutic advantages to these findings not previously studied with respect to prostate biopsies alone, which includes avoidance of active surveillance and possibly focal therapy and perhaps calling for an aggressive lymph node dissection, it is important to consider that the relatively high false negative detection rate of IDC/Crib in biopsies may affect treatment outcomes significantly. Additionally, the accuracy of PSMA PET–CT for lymph node staging of prostate cancer is 86.5% (95% CI 0.74-0.94; P = .06) with sensitivity of 58.3% and specificity of 95%, 4 which although highly acceptable for clinical decision-making, does raise a concerning question for possible overdiagnosis and therefore does not equate to tissue-based diagnosis. In fact, the only cohort of patients who actually went on to have radical prostatectomy and were included in this study had no statistically significant correlation with the presence of IDC/Crib finding on prostate biopsy.…”