Clinical Usefulness of PSMA PET/CT Imaging in Patients with Suspected Recurrence of Prostate Cancer after Primary RT with PSA below the Phoenix Criteria Threshold: Systematic Review and Meta-Analysis

Abstract

To assess the detection rate and the patterns of PSMA PET/CT uptake in patients with suspected prostate cancer recurrence after primary radiotherapy with serum PSA levels below the accepted Phoenix definition criteria for biochemical recurrence. The meta-analysis was performed according to the PRISMA statement. Studies providing data on patients with suspected prostate cancer recurrence after primary radiotherapy with serum PSA levels below the accepted Phoenix definition criteria were included. Atotal of 5 studies included a total of 1334 patients, of which 489 patients with suspected BCR and serum PSA levels below the Phoenix criteria were included. The PSMA PET/CT detection rate (DR) was 60% for PSA <0.5 ng/mL, 76% for PSA 0.5-1 ng/mL, 81.03% for PSA 1-2 ng/mL, and 89.5% for PSA>2. No significant differences were found in the locations of PSMA-PET/CT uptake among those with PSA ≤2 ng/mL, compared with those meeting the Phoenix criteria. The PSMA-PET/CT uptake of local-only recurrence was more likely in patients with PSA <2 ng/mL (local-only recurrence PSA >2 ng/mL [40.07%] vs PSA <2 ng/mL [58.10%]), RR: 0.718 (95% CI: 0.579-0.892). Lymph node, bone, and visceral metastasis detection rates could be extracted from 3 studies (432 patients). For lymph nodes, the DR was 46% (95% CI: 38-54) in patients outside the Phoenix criteria threshold, and 50% (95% CI: 39-62) in patients with PSA>2 ng/mL. The DR for bone metastases was 19% (95% CI: 12-28) in patients outside the Phoenix criteria threshold, and 25% (95% CI: 19-31) in patients with PSA>2 ng/mL. The DR for visceral metastases was 3% (95% CI: 0-7) in patients outside the Phoenix criteria threshold, and 2% (95% CI: 0-4) in patients with PSA>2 ng/mL. The potentially salvageable disease was considered when all evidence of avid disease could be safely treated with local therapy. This data could be extracted from two studies (343 patients). A higher proportion of disease potentially amenable to salvage therapy was reported in patients outside the Phoenix criteria threshold [salvageable disease: PSA ≤2 ng/mL: 69% (95% CI: 57-80), and PSA >2 ng/mL: 61% (95% CI: 55-66). The pooled risk ratio meta-analysis showed no statistically significant differences between the two previous groups RR: 0.91 (95% CI: 0.75-1.10). PSMAPET/CT can detect prostate cancer recurrence in patients with PSA levels below the Phoenix criteria threshold (reaching up to 80%). Local-only recurrence detection by PSMA PET/CT was more likely in patients with PSA <2 ng/mL. The data from the present meta-analysis shows that a critical review of the Phoenix criteria in the era of PSMA PET/CT might be warranted. Nevertheless, the lack of anatomopathological validation and the retrospective nature of the studies are some of our limitations.