PSMA PET/CT patterns of recurrence after mono-brachytherapy in men with low and intermediate prostate cancer and subsequent management.

Abstract

Purpose: Brachytherapy as monotherapy is a recommended treatment option for men with low to intermediate risk prostate cancer. Local recurrence is difficult to identify. This study investigated PSMA PET/CT for recurrence after brachytherapy, as well as their subsequent management when recurrence occurred only within the prostate.

Methods: We performed a retrospective single-center analysis for patients who were treated with brachytherapy as monotherapy for prostate cancer from May 2002 to May 2021 and who underwent a PSMA PET/CT for BCR. We report the findings on PSMA PET/CT, quantitative parameters, as well as the later management of the patients.

Results: Forty patients were identified, who underwent PSMA PET/CT to investigate a rising PSA at a median (IQR) of 7 years (3.0-10.8) after initial therapy. Median (IQR) PSA at time of PSMA PET/CT was 6.54 ng/mL (3.9-15.5). On PSMA PET/CT, 20/40 (50%) men had prostate-only recurrence. Of the 20 patients with prostate-only recurrence, 8/20 (40%) had recurrence in a high-dose radiation zone, versus 7/20 (35%) in an under-covered zone. On PSMA PET/CT, recurrence within the prostate had median (IQR) SUVmax 10.4 (5.1-15.7) and volume 2.9 mL (2.0-11.2). Subsequent management of these patients with local recurrence included surveillance followed by ADT (9/20, 45%). For those with surveillance followed by ADT, the mean time before introduction of ADT was 4.1 years (range 1-8 years).