(P092) Initial Clinical Results of Intraoperatively Built Custom-Linked (IBCL) Seeds for Permanent Prostate Brachytherapy

Samuel L. Cooper, MD, Simon Brown, BS, Michael Ashenafi, MS, Harry Clarke, MD, PhD, David T. Marshall, MD; Medical University of South Carolina

Purpose: In 2007, in partnership with industry, we developed a novel technique of performing prostate brachytherapy using intraoperatively built custom-linked (IBCL) seeds by means of the QuickLink device (C.R. Bard, Inc). We were the first in the world to use this technology for this purpose. We report the initial prostate-specific antigen (PSA) control and toxicity profile of patients treated using IBCL seeds with the QuickLink device for permanent prostate brachytherapy.

Materials and Methods: From March 2007 to July 2012, 148 patients with clinically localized prostate cancer underwent brachytherapy with IBCL seeds using real-time ultrasound-guided seed placement and intraoperative dosimetry to optimize target coverage. Real-time planning and seed placement were based on the approach of the Mount Sinai group reported by Stock and colleagues. All patients underwent postoperative CT-based dosimetric analysis. Patients were grouped per National Comprehensive Cancer Network (NCCN) risk stratification. Percent biochemical disease-free survival (bDFS) was calculated using Kaplan-Meier estimates with PSA relapse using the Phoenix definition as the event. Specific endpoint analyses were bDFS, Common Terminology Criteria for Adverse Events version 4.03 (CTCAE v4.03) toxicity grade 3 or greater, any urinary retention requiring catheter placement, any hematuria, and any rectal bleeding.

Results: A total of 148 patients with a median follow-up of 2.7 years were identified. Median age at diagnosis was 64.4 years, and 65.5% were white. Median PSA at diagnosis was 5.73 ng/mL. NCCN risk groups were as follows: low-risk 45%, intermediate-risk 46%, and high-risk 9%. In total, 76 patients received I-125 alone, and 71 patients received Pd-103 plus external beam radiotherapy (EBRT). One patient received Pd-103 alone. Median prostate D90 was 176.9 Gy for I-125 and 111.1 Gy for Pd-103. Median prostate V100, urethra D₃₀, and rectal V100 were 94.2%, 133.5%, and 0.55 cc, respectively. Five-year bDFS was 88.1% for intermediate-/high-risk patients. There were no failures in the low-risk group. The 5-year rates of grade 3 toxicity, urinary retention requiring catheterization, any hematuria, and any rectal bleeding were 3.8%, 5.3%, 12.2%, and 13.7%, respectively. Only one patient with rectal bleeding had radiation therapy (RT) changes on colonoscopy. All hematuria resolved on its own, with no RT changes at cystoscopy. For patients with at least 2 years of follow-up, median American Urological Association (AUA) symptom score and urinary quality of life peaked within 6 months of brachytherapy and returned to baseline between 2 and 3 years.

Conclusion: With early follow-up, this novel approach for permanent prostate brachytherapy in patients with clinically localized prostate cancer is associated with low rates of biochemical failure and toxicity.