Abstract Code: IUC26615-85

Are PSMA (Prostate-Specific Membrane Antigen) PET-CT scans in our unit requested according to NHS England Commissioning Criteria on prostate cancer?

1. Ditri ¹, O.S. Aung ², M. Ibrahim ¹, S. Madaan ³

(1) Darent Valley Hospital – United Kingdom, (2) Kent and Medway Medical School – United Kingdom, (3) London – United Kingdom

Objective

To assess unit compliance with NHS England Prostate-Specific Membrane Antigen (PSMA) PET-CT commissioning policy and evaluate reasoning for non-compliant requests. Guideline inclusion criteria require patients to be ≥18 years old and meet one of two indications: 1) Staging high-risk primary prostate cancer (Prostate-Specific Antigen (PSA) >20 ng/mL, Stage ≥T3, or Gleason ≥8) with equivocal baseline imaging, or 2) Biochemical recurrence localisation (PSA ≥0.2 ng/ml post-radical prostatectomy [RALP], or ≥2 ng/ml above nadir post-radiotherapy) in patients suitable for salvage therapy.

Methods

We conducted a retrospective audit of all prostate cancer patients who underwent a PSMA-PET scan at Darent Valley Hospital over a 12-month period in 2025. A total of 148 patients were identified, representing 183 distinct PSMA-PET scans. Patients were stratified into three clinical subgroups: Group 1 included patients at initial diagnosis (n=83); Group 2 post-radical prostatectomy (RALP) patients (n=45); and Group 3 post-radiotherapy patients (n=20). 

Results

Overall scan compliance was 80% (Group 1: 86.7%; Group 2: 84.4%; Group 3: 75%). 

In Group 1, 22 scans were positive for non-organ confined disease, only two of which were classified as non-indicated. 

In Group 2, diagnostic yield correlated strongly with Prostate-Specific Antigen (PSA) levels. When PSA was <0.2 ng/ml (n=8), 0% of scans were positive. PSMA-PET positivity rates increased to 33.3% for PSA 0.2-0.3 ng/ml (n=15), 71.4% for PSA 0.3-0.5 ng/ml (n=7), and 80% for PSA >0.5 ng/ml (n=15). All positive scans in this post-RALP group were guideline-indicated. 

In Group 3, 15 scans were positive, two of which were non-indicated.  The primary reasons for non-indicated scan requests in Groups 2 and 3 included a rising PSA that remained below the formal biochemical recurrence threshold (<0.2 ng/ml post-RALP or <2 ng/ml above nadir post-radiotherapy). Across Groups 1 and 3, non-indicated scans were frequently driven by the need to investigate abnormalities detected on prior MRI or bone scans. 

Conclusions

Our unit demonstrates strong guideline adherence. Data supports current thresholds, highlighting a 0% positivity rate in post-RALP patients with PSA <0.2 ng/ml. Scans falling outside criteria are often justified by multidisciplinary team (MDT) clinical judgment to investigate early PSA rises or equivocal conventional imaging findings.