226P - Use of PSMA PET in metastatic castration-resistant prostate cancer (mCRPC)

Background

Prostate-specific membrane antigen (PSMA) PET/CT has demonstrated greater sensitivity than conventional imaging including CT Chest, Abdomen and Pelvis (CT CAP) and whole body bone scan (WBBS) in the detection of metastatic prostate cancer. While there is limited data supporting a role in the staging of mCRPC, PSMA PET/CT is increasingly performed in this setting. Given the recent approval of novel therapeutic agents for non-metastatic (M0) CRPC, based on CT and WBBS findings, the increased accuracy of PSMA PET/CT is likely to alter the M0 population and influence the use of these treatments. Our study examines the impact of PSMA PET/CT in Australian mCRPC patients.

Methods

The multi-centre electronic CRPC Australian database (ePAD) was interrogated to identify mCRPC patients with available PSMA PET/CT for central review, prior to first line treatment for CRPC. Findings from PSMA PET, concurrent CT (with or without contrast) and whole body bone scan (WBBS) were analysed, particularly metastatic sites including pelvic lymph nodes (LN), distant LN, bone and viscera. Descriptive statistics were used to report differences between PSMA PET/CT, conventional CT and/or WBBS.

Results

Of the 603 eligible patients enrolled within ePAD between 2016 and 2019, 90 (15%) had mCRPC and an available PSMA PET/CT for central review. Fifteen (17%) also had dedicated CT imaging, 8 (9%) had concurrent WBBS, 10 (11%) had both dedicated CT and WBBS, while 57 (63%) only had concurrent low dose CT. Within our mCRPC PSMA PET cohort 10 (11%) had M0 disease based on CT and/or WBBS, in whom metastatic disease was only detected by PSMA PET/CT. Nine of these patients subsequently commenced systemic therapy. PSMA PET identified additional metastases in 39 (43%) patients when compared to CT and/or WBBS, including 29 (29%) patients in whom additional metastatic sites were identified PSMA PET most commonly detected additional bone metastases (28%) followed by pelvic LN (15%) or distant LN (8%).

Conclusions

In our real-world cohort, PSMA PET/CT was commonly performed without conventional imaging for mCRPC. PSMA PET/CT also demonstrated increased sensitivity for detection of metastases. The clinical impact of treatment decisions based on PSMA PET/CT findings in mCRPC requires further evaluation.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.