Risk group stratification in patients undergoing permanent 125I prostate brachytherapy as monotherapy

Kwok, Young; DiBiase, Steven J; Amin, Pradip P; Naslund, Michael; Sklar, Geoffrey; Jacobs, Stephen C

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Volume 53, Issue 3 , Pages 588-594, 1 July 2002

Risk group stratification in patients undergoing permanent ¹²⁵I prostate brachytherapy as monotherapy

Young Kwok, M.D.
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
Steven J DiBiase, M.D.
- Reprint requests to: Steven J. DiBiase, M.D., Department of Radiation Oncology, University of Maryland Medical Center, 22 S. Greene St., Baltimore, MD 21201 USA. Tel: 410-328-2318; Fax: 410-328-5279
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
Pradip P Amin, M.D.
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
Michael Naslund, M.D.
- Department of Urology, University of Maryland School of Medicine, Baltimore, MD, USA
Geoffrey Sklar, M.D.
- Department of Urology, University of Maryland School of Medicine, Baltimore, MD, USA
Stephen C Jacobs, M.D.
- Department of Urology, University of Maryland School of Medicine, Baltimore, MD, USA

Received 1 November 2001; received in revised form 25 January 2002; accepted 6 February 2002.

Abstract

: Patients undergoing prostate brachytherapy (PB) as monotherapy are often selected on the basis of favorable pretreatment factors. However, intermediate and high-risk prostate cancer patients are commonly offered PB as monotherapy without the addition of external beam radiotherapy (EBRT) or hormonal therapy. This series reports the outcome of patients undergoing PB as monotherapy who were stratified into low, intermediate, and high-risk groups with extended follow-up.

: A total of 102 patients with linically localized prostate cancer underwent PB alone as monotherapy. EBRT or hormonal therapy was not part of their initial treatment. Prostate-specific antigen (PSA) relapse-free survival (PRFS) was determined in accordance with the American Society for Therapeutic Radiology and Oncology consensus statement. Patients were stratified as at favorable risk (Stage T1-2a, pretreatment PSA ≤10.0 ng/mL, and Gleason score ≤6), intermediate risk (one prognostic indicator with a higher value), or unfavorable risk (≥2 indicators with higher values). The median follow-up period for patients in this series was 7 years (range 2.1–9.7). The median age at treatment was 71 years (range 54–80), and the median prescribed dose of ¹²⁵I was 145 Gy.

: Forty patients experienced a biochemical relapse at a median of 1.9 years (range 0.4–4.2). The 5-year actuarial PRFS rate for patients with favorable, intermediate, and unfavorable risk was 85%, 63%, and 24%, respectively (p <0.0001). All but 1 patient had the relapse within the first 5 years of treatment. When stratifying patients on the basis of their pretreatment PSA level, the 5-year PRFS rate for men with a PSA ≤10 ng/mL vs. >10 ng/mL was 78% vs. 35%, respectively (p = 0.0005). Furthermore, the 5-year PRFS rate for men with a Gleason score of ≤6 vs. ≥7 was 74% vs. 33%, respectively (p = 0.0001). No difference was found between Stage T1-T2a and Stage T2b or higher (64% vs. 54%, respectively; p = 0.353).

: On the basis of risk stratification, PB as monotherapy produces comparable PRFS to EBRT and surgery at 7 years of follow-up. PB as monotherapy is particularly ineffective in patients with unfavorable risk factors, and additional therapy is warranted.