Molecular tumor volume on PSMA PET/CT is an independent imaging biomarker associated with progression-free survival in patients with oligorecurrent prostate cancer

The purpose of this study is to evaluate the PSMA PET imaging parameters in association with outcomes among patients with oligorecurrent prostate cancer. This retrospective single-center study included 101 patients (median age 71; interquartile range 65-75) with biochemically recurrent prostate cancer who underwent PSMA PET between May 2021 and May 2022, revealing 5 or fewer sites of metastases (oligometastatic disease). Multiple variables including maximum standardized uptake value (SUV_max), mean standardized uptake value (SUV_mean), and molecular tumor volume (MTV) were measured and analyzed on a per-patient basis, along with total MTV and molecular tumor burden (MTB). Multivariable Cox proportional-hazards regression models were used to identify factors associated with progression-free survival (PFS). PSMA PET revealed a total of 216 lesions across all patients, of which 134 (62.0%) involved the lymph nodes and 56 (25.9%) involved the bone. A total of 61 (60.4%) patients received combined metastasis-directed and hormone therapy, and 40 (39.6%) received hormone therapy only. The median subsequent follow-up from PSMA PET detection of oligorecurrent disease was 18.2 months (IQR 10.3-25.0). MTV on PSMA PET was associated with worse PFS (hazard ratio: 1.05, 95% CI 1.00-1.11; P = 0.04). Molecular tumor volume on PSMA PET is associated with worse clinical outcomes in patients with oligorecurrent prostate cancer.