HDR brachytherapy salvage for nodular prostate fossa recurrence: A mechanistic review and initial report of clinical outcomes

PURPOSE: Biochemical recurrence (BCR) occurs in approximately 30% of men after upfront prostatectomy (RP) for prostate cancer. Salvage fossa brachytherapy offers a promising local treatment option. Here we describe a salvage technique and report initial outcomes. MATERIALS AND METHODS: Patients with local BCR and no evidence of distant metastases were included. Clinical, toxicity and dosimetry were collected. RESULTS: At a single institution, 23 patients completed prostate fossa brachytherapy salvage. Seven patients had received prior pelvic EBRT for an initial recurrence after RP and received HDR BT as definitive treatment for a second local recurrence. The remaining 16 patients were treated with combination EBRT + BT for initial recurrence after RP. Median age was 69 and PSA prior to salvage was 1.12 ng/mL. Ten patients (43.5%) received androgen directed therapy at the time of salvage, and 13 (56.5%) received local therapy only. After median follow up of 12 months, the median PSA decreased to 0.1 ng/mL. Eight patients (34.8%) remain on ADT. All patients have local disease control. Three patients developed locoregional failures, and two developed distant metastases. There were 17 (73.9%) acute grade 1 GU toxicities, two acute grade 2 GU toxicities (8.7%), and a single grade 3 (4.3%) GU toxicity. There were 6 acute grade 1 GI toxicities (26.1%), and a single patient with late grade 3 GU toxicity (4.3%). No grade 4 or higher toxicities were reported. CONCLUSIONS: This study found prostate bed BT to be safe and feasible for patients with nodular prostate fossa recurrences in both the initial salvage and salvage reirradiation setting. On preliminary follow up, PSA control rates are acceptable.