Long-term biochemical outcomes using cesium-131 in prostate brachytherapy

PURPOSE: Long-term outcomes reveal equivalent biochemical outcomes with low-dose-rate (LDR) brachytherapy (BT) compared with radical prostatectomy and external-beam radiotherapy for the management of prostate cancer. Iodine-125, the most commonly used isotope, may be associated with long-term urinary consequences. Cesium-131 (Cs-131) has a higher dose rate and shorter dose delivery time, predicting a shorter duration of urinary morbidity. We report our institution's high-volume experience and the most mature data to date on outcomes with Cs-131 prostate BT. METHODS AND MATERIALS: 571 men (median age: 65.38 years) with low (55%)-, intermediate (36%)-, and high-risk disease (9%) received monobrachytherapy, dual-modality, or trimodality using Cs-131 at a single institution. Risk groups were defined according to the National Comprehensive Cancer Network definition. Median prescription dose for definitive LDR-BT and LDR-BT boost was 115 Gy and 70 Gy, respectively. Median initial PSA was 6.1 ng/mL (IQR: 4.6-8.7). RESULTS: Median followup time was 5 years. 5/7-year overall survival for low-, intermediate-, and high-risk patients was 96.9%/96/9%, 92.8%/89.7%, and 95.8%/87.1%, respectively (p = 0.02). 5/7-year freedom from biochemical failure for low-, intermediate-, and high-risk patients was 98.5%/96.3%, 94.1%/86.4%, and 93.2%/74.5%, respectively (p < 0.01). 5/7-year prostate cancer-specific survival was 100%/100%, 99.3%/199.3%, and 98.0%/98.0% for low-, intermediate-, and high-risk patients, respectively (p < 0.01). CONCLUSIONS: Cs-131 is a viable alternative isotope for prostate brachytherapy for organ-confined disease. Long-term biochemical control and survival outcomes are excellent and on par with those attained with the use of I-125 or Pd-103. This report therefore supports the continued use of Cs-131 as an effective and comparable alternative isotope. Published by Elsevier Inc. on behalf of American Brachytherapy Society.