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

Jacob Ingvar; Erland Hvittfeldt; Elin Trägårdh; Athanasios Simoulis; Anders Bjartell

doi:10.1186/s13550-022-00918-7

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

EJNMMI Res. 2022 Aug 9;12(1):48. doi: 10.1186/s13550-022-00918-7.

Authors

Jacob Ingvar^{1

2}, Erland Hvittfeldt^{3

4

5}, Elin Trägårdh^{3

4

5}, Athanasios Simoulis^{3

6}, Anders Bjartell^{7

3}

Affiliations

¹ Department of Urology, Skåne University Hospital, Malmö, Sweden. Jacob.ingvar@skane.se.
² Department of Translational Medicine, Faculty of Medicine, Lund University, Jan Waldenströmsgata 5, 205 02, Malmö, Sweden. Jacob.ingvar@skane.se.
³ Department of Translational Medicine, Faculty of Medicine, Lund University, Jan Waldenströmsgata 5, 205 02, Malmö, Sweden.
⁴ Clinical Physiology and Nuclear Medicine, Skåne University Hospital, Malmö, Sweden.
⁵ Wallenberg Centre for Molecular Medicine, Lund University, Lund, Sweden.
⁶ Department of Pathology, Skåne University Hospital and Lund University, Malmö, Sweden.
⁷ Department of Urology, Skåne University Hospital, Malmö, Sweden.

Abstract

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. 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.

Keywords: Lymph node dissection; Metastases; PET/CT; Prostate cancer; Robotic surgery; Staging.

Grants and funding

#CAN 2018/522/Cancerfonden