External beam radiotherapy for clinically node-negative, localized hormone-refractory prostate cancer: impact of pretreatment PSA value on radiotherapeutic outcomes

Abstract

Purpose To analyze the results of clinically node-negative, localized hormone-refractory prostate cancer treated with external beam radiotherapy (EBRT) and to investigate the potential prognostic factors that influenced the therapeutic outcome. Methods and materials Fifty-three patients who had developed localized hormone-refractory prostate cancer were treated with EBRT between 1994 and 2001. According to the 1992 American Joint Committee on Cancer clinical stage, 4 patients had T2 and 49 had T3 at the start of RT, and 14 patients had a Gleason score <7, 14 had a Gleason score of 7, and 23 had a Gleason score of 8–10. All patients were treated with EBRT using the unblocked oblique four-field technique, with a total dose of 69 Gy. The fraction dose was 3 Gy three times weekly. The median follow-up after RT was 35 months (range, 8–96 months) and after androgen ablation was 73 months (range, 42–156 months). Results Of 53 patients, 15 patients subsequently developed clinical relapse, including locoregional and/or distant metastases. The site of first relapse was bone metastasis in 10, lymph nodes in 3, and local failure in 2 patients; 3 patients died of prostate cancer during the analysis period. The 3-year and 5-year cause-specific survival rate was 94% and 87%, respectively, and the 3-year and 5-year clinical relapse-free survival rate was 78% and 56%, respectively. The univariate analysis revealed that a short prostate-specific antigen (PSA) doubling time and high PSA value at the start of RT and a high Gleason score were statistically significant factors for the risk of clinical relapse. Multivariate analysis demonstrated that the PSA value (PSA ≤15 vs. ≥15 ng/mL) at the start of RT was an independent prognostic factor. Conclusion EBRT could be a treatment of choice for clinically node-negative, localized, hormone-refractory prostate cancer.