Session Item

Rate of biochemical recurrences in men affected by localized prostate cancer (pT2-3, N0) after radical prostatectomy (RP) ranges between 20 and 50%. Biochemical recurrence can be managed with curative purpose through salvage radiation therapy (SRT). However, positive metabolic imaging detecting local recurrence negatively impacts outcomes after SRT in this setting. Increasing radiation dose in this setting may improver relapse-free survival according to literature data, and stereotactic salvage radiotherapy (SSRT) in this setting has been shown to be a promising approach, achieving acceptable toxicity rates. STARR trial (STereotactic sAlvageRadiotherapy for macroscopic prostate bed Recurrence after prostatectomy-NCT05455736), is a prospective trial including patients affected by macroscopic prostate bed recurrence undergoing stereotactic radiotherapy on prostate bed. This trial is currently running in Florence radiotherapy department, here we present an early analysis from first cohort of patients enrolled.

Patients affected by biochemical recurrence (PSA > 0.2 ng/ml) after radical prostatectomy, in whom macroscopic prostate bed recurrence was detected through PSMA or Choline PET and confirmed through Magnetic resonance Imaging (MRI) were enrolled within this trial. All patients underwent Cyberknife stereotactic SSRT on macroscopic prostate bed relapse with a total dose of 35 Gy in 5 fractions. Concomitant Androgen Deprivation Therapy (ADT) is not allowed (adjuvant ADT after radical prostatectomy should have ended > 12 months before enrollment). Complete biochemical response (CBR) and Biochemical response (BR) were defined as a PSA nadir < 0.2 ng/ml and < 50% of baseline, respectively. Acute Gastrointestinal (GI) and Genitourinary (GU) Toxicity was assessed every 3 months after treatment according to Common Terminology Criteria for Adverse Events (CTCAE) score v.4.03. 

Twenty five patients have been enrolled since March 2021. Of these, 16 patients had at least 3 months of follow up after their treatment and were evaluable for early response and acute toxicity. Overall, CBR and BR were detected after 3 months in 4 (25%) and 9 (56.2%) of cases, respectively. One patient had biochemical progression at first evaluation and started ADT, 6 patients had stable PSA if compared to baseline and continued observation. Adverse events were recorded in 2 patients, one patient reported G2 GI and G1 GU toxicity, and G1 GU toxicity was reported in another case.

Promising results after SSRT for macroscopic prostate bed relapse were confirmed, with more than half of patients experienging BR. Reported toxicity was mild. Early report from this study reassure about feasibility of SSRT approach in this particular setting.