In Reply

Letters to the Editor Imaging of Prostate Cancer by Prof. Dr. med. Dipl.-Phys. Heinz-Peter Schlemmer, Prof. Dr. med. Bernd Joachim Krause, Dr. med. Viktoria Schütz, Prof. Dr. med. David Bonekamp, PD Dr. med. Sarah Marie Schwarzenböck, and Prof. Dr. med. Markus Hohenfellner in issue 42/2021

The numbers in our article (1) were cited from the original publications they came from. In most cases, sensitivity and specificity were reported as integers. Two decimals were reported only for the 95% confidence intervals.

Prostate specific membrane antigen (PSMA) is a transmembrane glutamate carboxypeptidase, which is highly expressed on prostate cancer cells. The target structure and binding site of the “small molecules” were characterized in seminal studies (2, 3). The specificity for PSMA-PET hybrid imaging (PET, positron emission tomography) has been reported as >90% in systematic reviews and meta-analyses and among the currently available imaging technologies represents the method with the highest specificity (reference citations in the article). On this background, a case where a months-old bone fracture shows PSMA concentrations on PET hybrid imaging seems highly unlikely—unless the fracture is a pathological fracture of a metastasis of the prostate cancer, in which even months later, the target structure PSMA is expressed in prostate cancer cells.

The current S3 guideline provides negative recommendations regarding the primary detection/diagnostic evaluation (4):

• Chapter 5.2.2. Rebiopsy: “PET/CT should not be used for the primary diagnostic evaluation” (5.19).
• Chapter 5.3. Staging: Patients with tumor category cT1 and low-risk parameters should not undergo imaging investigations (sonography, skeletal scintigraphy, CT, PET/CT) for the purpose of cancer staging” (5.21).

Chapter 5.3. Staging gives only one positive recommendation for using PSMA-PET hybrid imaging in the context of staging in prostate cancer: it can be used for diagnosing tumor spread in primary high-risk prostate cancer (Gleason score ≥ 8 or T category ≥ T3 or PSA ≥ 20 ng/mL) (5.29b).

DOI: 10.3238/arztebl.m2022.0115

On behalf of the authors
Prof. Dr. med. Bernd Joachim Krause
Klinik und Poliklinik für Nuklearmedizin
Universitätsmedizin Rostock

Conflict of interest statement

The author received consultancy fees from Terumo, PSI, Adacap/Novartis, and ITM. He was reimbursed travel expenses by Adacap/Novartis. He received lecture honoraria from Adacap/Novartis, ITM, Astellas, and Janssen. He received study support (third party funding) from Adacap/Novartis, Piramol, and Amgen. He is president of the German Society for Nuclear Medicine.

References

1. Schlemmer HP, Krause BJ, Schütz V, Bonekamp D, Schwarzenböck S, Hohenfellner M: Imaging of prostate cancer. Dtsch Arztebl Int 2021; 118: 713–9

2. Horoszewicz JS, Kawinski E, Murphy GP: Monoclonal antibodies to a new antigenic marker in epithelial prostatic cells and serum of prostatic cancer patients. Anticancer Res 1987; 7 (5B): 927–35.

3. Eder M, Schäfer M, Bauder-Wüst U, et al.: 68Ga-complex lipophilicity and the targeting property of a urea-based PSMA inhibitor for PET imaging. Bioconjug Chem 2012; 23: 688–97

4. Grimm MWS, Böhmer D, Bolenz C, et al.: Leitlinienprogramm Onkologie (Deutsche Krebsgesellschaft, Deutsche Krebshilfe, AWMF): S3-Leitlinie Prostatakarzinom, Langversion 6.0, 2021, AWMF Registernummer: 043/022OL, www.leitlinienprogramm-onkologie.de/leitlinien/prostatakarzinom/ (last accessed on 27 June 2021).