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Open Access Research article

Minimal percentage of dose received by 90% of the urethra (%UD90) is the most significant predictor of PSA bounce in patients who underwent low-dose-rate brachytherapy (LDR-brachytherapy) for prostate cancer

Nobumichi Tanaka1*, Isao Asakawa2, Kiyohide Fujimoto1, Satoshi Anai1, Akihide Hirayama1, Masatoshi Hasegawa2, Noboru Konishi3 and Yoshihiko Hirao1

Author Affiliations

1 Department of Urology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-8522, Japan

2 Department of Radiation Oncology, Nara Medical University, Nara, Japan

3 Department of Pathology, Nara Medical University, Nara, Japan

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BMC Urology 2012, 12:28  doi:10.1186/1471-2490-12-28

Published: 14 September 2012

Abstract

Background

To clarify the significant clinicopathological and postdosimetric parameters to predict PSA bounce in patients who underwent low-dose-rate brachytherapy (LDR-brachytherapy) for prostate cancer.

Methods

We studied 200 consecutive patients who received LDR-brachytherapy between July 2004 and November 2008. Of them, 137 patients did not receive neoadjuvant or adjuvant androgen deprivation therapy. One hundred and forty-two patients were treated with LDR-brachytherapy alone, and 58 were treated with LDR-brachytherapy in combination with external beam radiation therapy. The cut-off value of PSA bounce was 0.1 ng/mL. The incidence, time, height, and duration of PSA bounce were investigated. Clinicopathological and postdosimetric parameters were evaluated to elucidate independent factors to predict PSA bounce in hormone-naïve patients who underwent LDR-brachytherapy alone.

Results

Fifty patients (25%) showed PSA bounce and 10 patients (5%) showed PSA failure. The median time, height, and duration of PSA bounce were 17 months, 0.29 ng/mL, and 7.0 months, respectively. In 103 hormone-naïve patients treated with LDR-brachytherapy alone, and univariate Cox proportional regression hazard model indicated that age and minimal percentage of the dose received by 30% and 90% of the urethra were independent predictors of PSA bounce. With a multivariate Cox proportional regression hazard model, minimal percentage of the dose received by 90% of the urethra was the most significant parameter of PSA bounce.

Conclusions

Minimal percentage of the dose received by 90% of the urethra was the most significant predictor of PSA bounce in hormone-naïve patients treated with LDR-brachytherapy alone.

Keywords:
Prostate cancer; Brachytherapy; PSA bounce; Post-dosimetry; UD90 (%)