PACE-B
Trial question
Is SBRT noninferior to conventionally or moderately hypofractionated radiotherapy in patients with low-to-intermediate-risk localized prostate cancer?
Study design
Multi-center
Open label
RCT
Population
874 male patients.
Inclusion criteria: men with stage T1 or T2 prostate cancer, a Gleason score < 3+4, and a PSA level ≤ 20 ng/mL.
Key exclusion criteria: primary Gleason grade ≥ 4; any NCCN high-risk factors; previous pelvic radiotherapy; previous treatment for prostate cancer; prostheses in both hips.
Interventions
N=433 SBRT (36.25 Gy in 5 fractions over a period of 1 or 2 weeks).
N=441 conventionally or moderately hypofractionated radiotherapy (78 Gy in 39 fractions over a period of 7.5 weeks or 62 Gy in 20 fractions over a period of 4 weeks).
Primary outcome
Rate of freedom from biochemical or clinical failure at 5-years
95.8%
94.6%
95.8 %
71.8 %
47.9 %
23.9 %
0.0 %
Stereotactic body
radiotherapy
Conventionally or moderately hypofractionated
radiotherapy
Difference not exceeding
non-inferiority
margin ✓
Difference not exceeding non-inferiority margin in the rate of freedom from biochemical or clinical failure at 5-years (95.8% vs. 94.6%; HR 1.37, 90% CI 0.89 to 2.08).
Secondary outcomes
No significant difference in commencement of hormone therapy (2.3% vs. 4.3%; HR 0.55, 95% CI 0.26 to 1.2).
No significant difference in overall survival (89.4% vs. 92.5%; HR 0.71, 95% CI 0.45 to 1.11).
No significant difference in disease-free survival (84.3% vs. 86%; HR 0.91, 95% CI 0.65 to 1.28).
Safety outcomes
No significant difference in cumulative incidence of late Radiation Therapy Oncology Group grade ≥ 2 gastrointestinal toxic effects at 5 years.
Significant difference in cumulative incidence of late Radiation Therapy Oncology Group grade ≥ 2 genitourinary toxic effects at 5 years (26.9% vs. 18.3%).
Conclusion
In men with stage T1 or T2 prostate cancer, a Gleason score < 3+4, and a PSA level ≤ 20 ng/mL, SBRT was noninferior to conventionally or moderately hypofractionated radiotherapy with respect to the rate of freedom from biochemical or clinical failure at 5-years.
Reference
Nicholas van As, Clare Griffin, Alison Tree et al. Phase 3 Trial of Stereotactic Body Radiotherapy in Localized Prostate Cancer. N Engl J Med. 2024 Oct 17;391(15):1413-1425.
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