Clinical impact of whole-body ⁶⁸Ga-PSMA I&T PET/CT: lesion frequency and added benefit in lower extremities

Abstract

Aim Few small-scaled studies performed systematic analysis of the benefits of extending prostate specific membrane antigen positron-emission tomography/ computed tomography (⁶⁸Ga-PSMA I&T PET/CT) to the lower extremities in prostate cancer (PCa) patients. We hypothesized that ⁶⁸Ga-PSMA I&T PET/CT positive lesions are rare in lower extremities of prostate cancer (PCa) patients, the clinical implication is negligible and may therefore be omitted.

Methods We retrospectively analyzed 1,068 PCa patients who received ⁶⁸Ga-PSMA I&T PET/CT in a single institution (2016–2018). Of those, 285 (26.7%) were newly diagnosed, 529 (49.5%) had biochemical recurrence (BCR) and 254 (23.8%) were castration-resistant prostate cancer (CRPC) patients.

Results Of 1,068 ⁶⁸Ga-PSMA I&T PET/CTs, positive lesions in the lower extremities were identified in 6.9% patients (n=74). Positive lesions in the lower extremities were most common in CRPC patients (19.7%; n=50), followed by newly diagnosed (3.2%; n=9) and BCR (2.8%; n=15) PCa patients. Only 3 patients presented with exclusive lesions in the lower extremities, respectively 0.8% (n=2) in CRPC and 0.4% (n=1) in newly diagnosed PCa. Both CRPC (94.1%, n=47) and BCR (80.0%, n=12) patients with PSMA-positive lesions predominantly received systemic therapy.

Conclusion Identification of lower extremities lesions with PSMA PET/CT is uncommon and exclusive lesions are rare. PSMA PET/CT findings of the lower extremities did not change therapy management. Thus, scanning of the lower extremities can be omitted in standard protocols.

Zusammenfassung

Ziel Nur wenige, klein angelegte Studien untersuchten systematisch den Nutzen einer Erweiterung der Prostata-spezifischen Membranantigen-Positronen-Emissions-Tomografie/Computertomografie (⁶⁸Ga-PSMA-I&T-PET/CT) auf die unteren Extremitäten bei Patienten mit Prostatakarzinom (PCa). Wir stellten die Hypothese auf, dass ⁶⁸Ga-PSMA-I&T-PET/CT-positive Läsionen in den unteren Extremitäten von PCa-Patienten selten sind, die klinische Relevanz geringfügig ist und die Untersuchung daher weggelassen werden kann.

Methoden Wir analysierten retrospektiv 1068 PCa-Patienten, die eine ⁶⁸Ga-PSMA-I&T-PET/CT in einer einzigen Einrichtung erhielten (2016–2018). Davon hatten 285 (26,7%) eine Erstdiagnose, 529 (49,5%) hatten ein biochemisches Rezidiv (BCR) und 254 (23,8%) hatten ein kastrationsresistentes Prostatakarzinom (CRPC).

Ergebnisse Von 1068 ⁶⁸Ga-PSMA-I&T-PET/CTs wurden bei 6,9% der Patienten (n=74) positive Läsionen in den unteren Extremitäten identifiziert. Positive Läsionen in den unteren Extremitäten waren am häufigsten bei CRPC-Patienten (19,7%; n=50), gefolgt von neu diagnostizierten (3,2%; n=9) und BCR (2,8%; n=15) PCa-Patienten. Nur 3 Patienten wiesen ausschließlich Läsionen in den unteren Extremitäten auf, jeweils 0,8% (n=2) bei CRPC und 0,4% (n=1) bei neu diagnostiziertem PCa. Sowohl CRPC- (94,1%, n=47) als auch BCR-Patienten (80,0%, n=12) mit PSMA-positiven Läsionen erhielten überwiegend eine systemische Therapie.

Schlussfolgerung Die Identifizierung von Läsionen der unteren Extremitäten mit PSMA-PET/CT ist selten und exklusive Läsionen sind selten. PSMA-PET/CT-Befunde der unteren Extremitäten änderten das Therapiemanagement nicht. Daher kann bei Standardprotokollen auf die Untersuchung der unteren Extremitäten verzichtet werden.

Schlüsselwörter

Prostatakarzinom - Knochenmetastasen - biochemisches Rezidiv - CRPC - PSMA-PET/CT - primäres Staging

Keywords

prostate cancer - bone metastases - biochemical recurrence - CRPC - PSMA-PET/CT - primary staging

Publication History

Received: 07 December 2020

Accepted after revision: 01 July 2021

Article published online:
20 August 2021

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