Moderate dose escalation with single-fraction high-dose-rate brachytherapy boost for clinically localized intermediate- and high-risk prostate cancer: 5-year outcome of the first 100 consecutively treated patients

Purpose: To analyze the clinical outcome and toxicity data of the first 100 consecutive patients treated with a single-fraction high-dose-rate brachytherapy (HDR-BT) and external beam radiotherapy (EBRT).

Methods and materials: Two-hundred eighty patients have been treated with HDR-BT boost for localized intermediate- to high-risk prostate cancer. Among these, the outcome and toxicity of the first 100 patients treated with a single HDR-BT fraction were assessed. A median dose of 60Gy EBRT was given to the prostate and vesicles. Interstitial HDR-BT of 10Gy was performed during the course of EBRT.

Results: Median followup time was 61.5 months. The 5-year actuarial rates of overall survival, cause-specific survival, disease-free survival, and biochemical no evidence of disease (bNED) for the entire cohort were 93.3%, 99.0%, 89.3%, and 85.5%, respectively. The 7-year actuarial rate of bNED was 84.2% for the intermediate-risk group and 81.6% for the high-risk group (p=0.8464). The 7-year actuarial rates of bNED for Grade 1, 2, and 3 tumors were 97.5%, 80.0%, and 67.1%, respectively. The 5-year probability for developing late Grade 3 gastrointestinal and genitourinary (GU) toxicity was 2.1% and 14.4%, respectively. Grade 3 GU complications occurred significantly more frequently in patients with a history of preirradiation transurethral resection (29.1% vs. 8.8%; p=0.0047).

Conclusions: Five-year outcome after 60Gy EBRT plus a single fraction of 10Gy HDR-BT boost is encouraging. Preradiation transurethral resection significantly increases the risk of late severe GU complications.