Preliminary Results of a Pilot Study of Focal Salvage High-Dose-Rate Prostate Brachytherapy in Patients with Local Recurrence after Definitive External Beam Radiotherapy

Abstract

Purpose: Permanent prostate implants (PPI) are performed since 1994 in our institution. The analysis of 1794 patients treated between 1994 and 2012 was done to evaluate the seed loss and migration rate over this period. The impact of implantation techniques on seed migration, such as the introduction of intraoperative technology, was evaluated. The correlation between seed loss/migration and the experience of the physician performing the implant was also explored. Materials and Methods: Post-implant evaluations were done 30 days after the implant for all patients. Migration was defined as one or more seed found outside the prostate region and confirmed by imaging (CT or kV). Most of the time, the migrated seeds were located in the lungs while uncommon locations included kidneys, heart and sacrum. Seed loss was defined as at least one seed missing at the post-implant evaluation, excluding the migrated seeds found in the patient. Seeds might be lost through micturition but miscount on kV images remains a possibility. Since January 2004, all PPI patients were surveyed using a collimated NaI gamma scintillator to detect seed migration to the chest. Before this date, the total number of migrated and lost seeds is reported without differentiation. The seed loss and migration rate are reported for three different implantation techniques: manual, guidance and robotic. The manual group (G1) consists of implants performed with a pre-planning technique and 2D TRUS insertion. The guidance group (G2) were done using OR planning and 3D TRUS insertion with guidance (SPOTPRO, Nucletron). The robotic group (G3) were implanted with the FIRST system (Nucletron) similar to the second group G2 but with robotic needle extraction. Groups were compared using Pearson khi-2 test. Results: The proportions of patients with seed migration were 17%, 15.5% and 8% for the G1, G2 and G3 groups respectively. The difference between G1-G3 or G2-G3 are statistically significant (p5 0.0028 and 0.002). For patients with either migration or loss, rates were 39%, 26% and 23.6% for the G1, G2 and G3 groups, respectively. There is a significant difference between G1-G3 (p 5 0.0005). The introduction of intra-op planning between 2003 and 2004 had a significant impact on both migration and seed loss rates (p50.0049). The rate of seed migration/loss tended to decrease as physicians gained experience in the implantation technique. Conclusions: Seed migration and loss rates are related to the implantation technique, with the robotic-assisted technique leading to the best results. Data also suggest that the experience of the physician performing the implant has an impact on migration/loss rates. PD56