# Does total lesion prostate‐specific membrane antigen (PSMA) activity on 68Ga‐PSMA PET/CT correlate with PSA and prostatectomy histopathological/clinical outcomes in patients with localised primary prostate cancer?

## TL;DR

This study shows that total lesion PSMA activity on PET scans correlates with PSA levels and prostate cancer outcomes, suggesting it could help predict disease progression.

## Contribution

The study introduces PSMATL as a potential new prognostic tool for localized prostate cancer.

## Key findings

- PSMATL correlates with PSA, PSA density, and histopathological features like tumor grade and stage.
- Higher PSMATL is associated with a 1% increased risk of biochemical recurrence per unit increase.
- PSMATL was significantly higher in patients with aggressive features like lymphovascular invasion.

## Abstract

To evaluate the relationship between total lesion PSMA (PSMATL), serum PSA, histopathological findings and biochemical recurrence (BCR) in patients with localised prostate cancer (PCa).

This retrospective study assessed men undergoing 68Ga‐PSMA‐11 PET/CT for newly diagnosed or treatment‐naïve PCa localised to the prostate gland. Volumes of interest were manually mapped to derive SUVmax, SUVmean, PSMA‐avid tumour volume and PSMATL. PSMATL was defined as the product of PSMA‐avid primary tumour volume and SUVmean. Spearman correlation tests evaluated associations between PET parameters and PSA, ISUP GG and radical prostatectomy (RP) histopathological outcomes. Associations between PET parameters and clinical outcomes were determined using Cox proportional hazards regression with results presented as HR and 95% CI.

A total of 200 patients were included, with a median age of 68 (IQR 62–73) years, PSA of 9.5 (6.6–13.0) ng/ml and follow‐up of 41 (25–60) months. Median PSMATL was 29.6 (14.8–54.8) and SUVmax 11.0 (6.8–17.9). PSMATL and SUVmax demonstrated a weak correlation with baseline PSA (ρ = 0.334, p < 0.001 and ρ = 0.343, p < 0.001), and PSMATL showed a weak correlation with PSA density in the RP subgroup (ρ = 0.242, p = 0.021). Among 109 (54.5%) patients undergoing RP, PSMATL and SUVmax showed a weak correlation with ISUP GG (ρ = 0.233, p = 0.015 and ρ = 0.340, p < 0.001). There was a weak correlation between PSMATL and primary tumour stage (ρ = 0.244, p = 0.010) and lymph node stage (ρ = 0.259, p = 0.007). PSMATL was significantly higher in those with seminal vesicle involvement (p = 0.011), perineural invasion (p = 0.025) and lymphovascular invasion (p = 0.002). BCR occurred in 46 patients (42%), with a 1% increased risk of BCR per unit increase in PSMATL (HR 1.01, 95% CI 1.00–1.02, p = 0.011).

PSMATL correlates with PSA, PSA density, ISUP GG, RP histopathological findings and BCR. As an adjunct to SUVmax, PSMATL has the potential to be a useful prognostic tool. Further research is needed to assess its clinical utility.