Single-dose High-dose-rate Brachytherapy Compared to Two and Three Fractions for Locally Advanced Prostate Cancer

Background: Single-dose high-dose-rate brachytherapy (HDR-BT), in a Phase-II study, was compared to two or three fractions in intermediate and high-risk localized prostate cancer.

Patients And Methods: 293 patients received 1×19Gy or 1×20Gy (A=49), 2×13Gy (B=138), or 3×10.5Gy (C=106) and assessed with prospective measures of serum PSA, late genitourinary (GU) and gastrointestinal (GI) morbidity using RTOG scales and the International Prostate Symptom Score (IPSS).

Results: Median follow-up is 49, 63 and 108months (A, B and C, respectively). At 4years biochemical relapse free survival was 94% (A), 93% (B) and 91% (C) (p=0.54). Risk-category was the only significant independent predictor of relapse (p<0.0001). Kaplan-Meier 4-year-estimates of GU-3 were 2% (A and B) and 11% (C). GI-3 was 0% (A and B) and 1% (C). No GU or GI grade-4 events were observed. IPSS≥20 was 11% (A), 9% (B) and 16% (C) (p=0.9). Prevalence of GU-3 was ≤4% in the 3 groups at all times; GI-3 was low or non-existent. Prevalence of catheter use was ≤6% in all groups.

Conclusions: A single dose of 19-20Gy achieves similar rates of late morbidity and biochemical control compared to 2 and 3 fractions.