We are seeing an increasing number of studies evaluating the role of fluorinated ligands for prostate-specific membrane antigen (PSMA) PET/CT. Data to this point in time has not shown any convincing diagnostic advantage or disadvantage with the use of either fluorine F 18 (F18 DCFPyL) and gallium (Ga) Ga68 HBEDD-11 PSMA PET/CT tracers although the former has obvious logistical benefits in busy nuclear medicine departments. This study by Witkowska-Patena and colleagues is amongst the first studies to look at a relatively new fluorinated tracer in the form of F18 PSMA-1007. This tracer is already becoming commercially readily available and well before we have good data on its utility and capability.
The justification for yet another PSMA tracer appears to be sound although this is not specifically discussed in the paper. The potential advantage of F18 PSMA-1007 is that there is significantly lower urinary excretion of the tracer; as a result, there is the minimization of tracer within the urine that could potentially impact the interpretation of tracer uptake in areas adjacent to the urinary tract.
Examples could include the interpretation of tracer in the region of the vesicourethral anastomosis following radical prostatectomy and lymph nodes adjacent to the anatomical path of the ureter.
The study population included 40 men who had prostate-specific antigen (PSA) biochemical failure following either radical prostatectomy or external beam radiotherapy or both. The PSA levels varied from technically undetectable levels through to 2ng/mL and the median PSA was 0.65ng/mL. Whilst this appears to be a wide range of PSA levels, this is a much tighter PSA range than most published studies with Ga68 HBEDD-11. Not surprisingly, the identification of metastases correlated with increasing PSA levels. The detection rates in the clinically significant zones of <0.5ng/mL and 0.5-<1.0ng/mL was 39% and 55% respectively. This study provides important early data insights into this new tracer but there remains a need for more data to keep pace with the increasing commercial availability of F18 PSMA-1007.
Written by: Henry Woo, MBBS, DMedSc, FRACS, Professor of Surgery, Sydney Adventist Hospital Clinical School, Professor of Robotic Cancer Surgery, Chris O'Brien LifeHouse.
- Witkowska-Patena, Ewa, Agnieszka Giżewska, Mirosław Dziuk, Jolanta Miśko, Anna Budzyńska, and Agata Walęcka-Mazur. 2019. "Diagnostic Performance Of 18F-PSMA-1007 PET/CT In Biochemically Relapsed Patients With Prostate Cancer With PSA Levels ≤ 2.0 Ng/Ml". Prostate Cancer And Prostatic Diseases 23 (2): 343-348. doi:10.1038/s41391-019-0194-6.
Read the Full-Text Article: Diagnostic Performance of 18F-PSMA-1007 PET/CT in Biochemically Relapsed Patients with Prostate Cancer with PSA levels ≤ 2.0 ng/ml