Role of isotope selection in long-term outcomes in patients with intermediate-risk prostate cancer treated with a combination of external beam radiotherapy and low-dose-rate interstitial brachytherapy - Abstract

OBJECTIVE:To examine the rates of long-term biochemical recurrence-free survival (BRFS) with respect to isotope in intermediate-risk prostate cancer treated with external beam radiotherapy (EBRT) and brachytherapy.

METHODS: A total of 242 consecutive patients with intermediate-risk prostate cancer were treated with iodine-125 (125I) or palladium-103 (103Pd) implants after EBRT (range 45.0-50.4 Gy) from 1996 to 2002. Of the 242 patients, 119 (49.2%) were treated with 125I and 123 (50.8%) with 103Pd. Multivariate Cox regression analysis was used to analyze BRFS, defined according to the Phoenix definition (prostate-specific antigen nadir plus 2 ng/mL) with respect to Gleason score, stage, pretreatment prostate-specific antigen level, and source selection. Late genitourinary/gastrointestinal toxicities were assessed using the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer scale.

RESULTS: At a median follow-up of 10 years, the BRFS rate was 77.3%. A statistically significant difference was found in the 10-year BRFS rate between the 125I- and 103Pd-treated groups (82.7% and 70.6%, respectively; P = .001). The addition of hormonal therapy did not improve the 10-year BRFS rate (77.6%) compared with RT alone (77.1%; P = .22). However, a statistically significant difference in the BRFS rate was found with the addition of hormonal therapy to 103Pd, improving the 10-year BRFS rate for (73.8%) compared with 103Pd alone (69.1%; P = .008). On multivariate analysis, isotope type (103Pd vs 125I), pretreatment prostate-specific antigen level >10 ng/mL, and greater tumor stage increased the risk of recurrence by 2.6-fold (P = .007), 5.9-fold (P < .0001), and 1.7-fold (P = .14), respectively.

CONCLUSION: 125I renders a superior rate of BRFS compared with 103Pd when used with EBRT. Hormonal therapy does not provide additional benefit in patients with intermediate-risk prostate cancer treated with a combination of EBRT and brachytherapy, except for the addition of hormonal therapy to 103Pd.

Written by:
Wernicke AG, Shamis M, Yan W, Trichter S, Sabbas AM, Goltser Y, Christos PJ, Brennan JS, Parashar B, Nori D. Are you the author?
Department of Radiation Oncology, Weill Medical College of Cornell University, New York, New York 10065, USA.

Reference: Urology. 2012 May;79(5):1098-104.
doi: 10.1016/j.urology.2012.01.043

PubMed Abstract
PMID: 22546388

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