# PSMA PET/CT findings in high‐risk biochemical recurrence after local treatment of prostate cancer

## TL;DR

This study shows that PSMA PET/CT scans detect cancer recurrence in most patients with high-risk prostate cancer after local treatment.

## Contribution

The study identifies patterns of cancer recurrence detected by PSMA PET/CT in high-risk prostate cancer patients and suggests potential treatment approaches.

## Key findings

- 77% of patients had at least one lesion detected on PSMA PET/CT.
- 40% of patients with metastatic disease had oligometastatic disease (1–3 lesions).
- Local recurrence was more common after radiation therapy, while nodal recurrence was more common after prostatectomy.

## Abstract

To describe PSMA PET/CT characteristics of patients with high‐risk BCR.

This was a retrospective analysis of patients with high‐risk BCR prostate cancer (PSA ≥ 2 ng/ml above nadir after radiation therapy [RT] or ≥1 ng/ml after radical prostatectomy [RP] +/− RT) who underwent PET/CT from July 2021–March 2023. Patients with prior cytotoxic chemotherapy, androgen deprivation therapy (ADT) initiated >3 months prior to PET/CT or positive conventional imaging within 3 months of PET/CT were excluded. Neoadjuvant/adjuvant ADT completed ≥9 months prior was allowed. Logistic regression, Pearson's Chi‐squared, Wilcoxon rank sum and Fisher's exact tests were used for analysis.

A total of 113 of 145 (77%) included patients in the analysis had ≥1 lesion on PSMA PET/CT. There was no difference in PSMA PET/CT positivity based on age, race, Gleason Grade at initial biopsy or PSA. Overall, 29 (20%) patients had lesions in the prostate/prostate bed only, 31 (21%) had lesions consistent with N1M0 disease and 53 (37%) had lesions consistent with M1 disease. For M1 patients, 21/53 (40%) had oligometastatic disease (1–3 lesions), and 32/53 (60%) had a higher burden (>3 lesions). Local recurrence was more common with RT and nodal recurrence with RP, with no difference in distant metastasis by initial treatment.

Nearly 80% of patients with high‐risk BCR after local treatment for prostate cancer with RP and/or RT will have positive findings on PSMA PET/CT. In addition to intensified systemic therapy, up to 55% of the patients may have benefitted from salvage local therapy, nodal pelvic radiation or metastasis‐directed therapies for oligometastatic disease.