A comparison of the impact of isotope ((125)I vs. (103)Pd) on toxicity and biochemical outcome after interstitial brachytherapy and external beam radiation therapy for clinically localized prostate cancer - Abstract

PURPOSE: To compare biochemical outcomes and morbidity associated with iodine-125 (125I) and palladium-103 (103Pd) brachytherapy as part of combined modality therapy for clinically localized prostate cancer.

METHODS AND MATERIALS: Between October 2002 and December 2008, 259 patients underwent prostate brachytherapy (125I prescription dose, 110Gy: n=199; 103Pd prescription dose, 100Gy: n=60) followed by external beam radiotherapy (median dose, 50.4Gy). Eighty-seven patients also received neoadjuvant androgen deprivation therapy. Toxicities were recorded with CTCAE v 3.0, International Prostate Symptoms Score (IPSS), and International Index of Erectile Function questionnaires.

RESULTS: Overall, acute Grade ≥2 genitourinary toxicity occurred in 21% and 30% of patients treated with 125I and 103Pd, respectively (p=0.16). There were no significant differences in IPSS change or urinary quality-of-life scores between the isotopes at 4, 6, or 12 months (p=0.20, 0.21, and 1.0, respectively). IPSS resolution occurred at a median of 11 and 6 months for 125I and 103Pd patients, respectively (p=0.03). On multivariate analysis, only the use of neoadjuvant androgen deprivation therapy was predictive of time to IPSS resolution (p=0.046). Late Grade ≥2 gastrointestinal toxicity occurred in 7% of 125I patients and 6% of patients treated with 103Pd. Of 129 potent patients at baseline, there was better erectile function in patients who received 103Pd (p=0.02); however, the followup was shorter for these patients. The 5-year prostate-specific antigen relapse-free survival for 125I and 103Pd patients was 95.2% and 98.2% (p=0.73), respectively.

CONCLUSION: There were no differences in acute or long-term genitourinary or gastrointestinal toxicity between 125I and 103Pd in combined modality therapy for prostate cancer. There may be less erectile toxicity with the use of 103Pd; however, additional followup of these patients is needed. There was no significant difference in 5-year prostate-specific antigen relapse-free survival between 103Pd and 125I.

Written by:
Kollmeier MA, Pei X, Algur E, Yamada Y, Cox BW, Cohen GN, Zaider M, Zelefsky MJ.   Are you the author?
Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY.

Reference: Brachytherapy. 2011 Dec 20. Epub ahead of print.
doi: 10.1016/j.brachy.2011.11.002

PubMed Abstract
PMID: 22192495

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