By Daniel A. Hamstra, MD, PhD, FASTRO, Baylor College of Medicine
The benefit of dose escalation with brachytherapy in intermediate-risk (IR) prostate cancer has been examined in several prior randomized trials. Sunday afternoon at ASTRO’s 68th Annual Meeting brought new results from an additional phase III trial of brachytherapy boost against dose-escalated EBRT specifically in IR disease. GETUG P05 randomized 298 men with intermediate-risk prostate cancer (PSA 10–20 ng/mL, and/or Gleason 7, and/or T2b) across 27 French centers. All received 46 Gy/2-Gy fractions to the prostate and proximal seminal vesicles, followed by either an EBRT boost to a total of 80 Gy, or a brachytherapy boost [I-125 LDR (110 Gy) or HDR (Ir-192, 14 Gy), with technique chosen by each center]. Unlike the two prior randomized brachytherapy boost trials, ADT was not allowed, making this a direct test of local dose alone.
Of 296 evaluable patients (155 EBRT, 141 brachytherapy: 79 LDR, 55 HDR), median age was 69, and 87.5% had Gleason 7 (60.5% 3+4, 27% 4+3). At a median follow-up of 61.7 months, there was no difference in the primary endpoint with five-year PSA-PFS of 87.8% after brachytherapy versus 88.8% after dose-escalated EBRT (p=0.86), with no difference by LDR or HDR and no benefit in either the 3+4 or 4+3 subgroup. Overall survival was also similar (96.0% vs 92.7%, p=0.30). Brachytherapy was associated with less acute GI toxicity (29.9% vs. 41.2%, p=0.03) without a difference in acute GU toxicity while late GU toxicity was higher with implant (82.2% vs. 63.3%, p=0.004) without differences in late GI toxicity; reassuringly these differences were in grade 1-2 toxicity, and there was no difference in grade 3 toxicity, quality of life or sexual function.
These results invite comparison with previous studies. ASCENDE-RT enrolled mostly high-risk patients and included both ADT and pelvic RT. It did show a brachytherapy benefit in PSA-PFS, though the advantage was greatest in higher-risk patients. The Mount Vernon randomized HDR boost trial also enrolled predominantly intermediate- and high-risk patients where ~76% received ADT, and it too showed improved PSA-PFS from HDR boost as early as 30 months which was sustained with longer follow-up. Nevertheless, in both previous trials it was hard to identify if PSA-PFS benefit was present in intermediate-risk patients at five years. Finally, RTOG 0232, in which all patients received brachytherapy, found no benefit from adding EBRT, albeit with more toxicity in the combined arm.
GETUG P05, therefore, fills an important gap: a population that was exclusively intermediate-risk, including a substantial Gleason 4+3 subgroup, compared against an adequately dose-escalated (80-Gy) EBRT arm without ADT. Although there was no benefit observed at this time, longer follow-up still matters for in ASCENDE-RT the arms diverged progressively over time (89% vs 84% PSA-PFS at five years and 83% vs 62% at nine years), and separation in GETUG P05 remains possible with further follow-up. For now, though, the message stands: in IR prostate cancer, adding a brachytherapy boost to EBRT did not improve five year PSA-PFS over dose-escalated EBRT alone. This does not diminish brachytherapy's established role; rather, it suggests that the benefit of extreme local dose escalation seen in high-risk-dominated populations should not be automatically extrapolated to every IR patient.
Ariane Lapierre, MD, PhD, the presenting author of the study noted “Ever since the ASCENDE-RT trial, the assumption was that higher radiation doses meant better outcomes. Our trial demonstrates the opposite: in intermediate-risk prostate cancer treated with radiotherapy alone, more is simply not better. Aggressive escalation increases late toxicities without offering a survival advantage. This confirms what current AUA/ASTRO and NCCN guidelines emphasize — brachytherapy boost regimens are unnecessary in this setting, and tailoring treatment means knowing when less intervention is genuinely better care”
Excitingly, at this meeting we will also see the long-term follow-up of the RTOG 0815 trial, which previously demonstrated that adding ADT to dose-escalated RT improved PSA-PFS, at the cost of ADT toxicity and without other significant clinical improvements. Finally, we will also see an abstract on the role of genomic profiling in that same trial. As a result, we continue to refine optimal treatment in the intermediate-risk space with dose, technique, ADT, and potentially genomics all playing a role, with GETUG P05 filling another key piece.
Abstract 105, Brachytherapy Versus External Beam Dose-Escalated Boost for Intermediate-Risk Prostate Cancer: Definitive Results of the GETUG P05 Trial, was presented during SS 02 - Escalate, De-escalate, or Substitute? Trials Shaping Prostate Cancer Care, at ASTRO's 68th Annual Meeting.
Published on: September 28, 2026
