KEY POINTS
- The prospective registry enrolled 191 patients at seven Austrian centres, with 169 included in the final analysis. Median age was 74 years, and median follow-up was 14 months.
- The cohort included 23.7% low-risk, 48.5% favourable intermediate-risk, and 27.8% unfavourable intermediate-risk prostate cancer. High-risk disease was not included.
- Every patient received linac-based 40 Gy in five fractions. Treatment was delivered on alternating weekdays in 61.5% and on consecutive weekdays in 38.5%.
- Technical practice varied substantially: gold fiducials were used in 89.9%, 3-mm posterior margins in 62.1%, ExacTrac monitoring in 30.8%, real-time electromagnetic tracking in 16.6%, and rectal spacers in 14.2%.
- Median PSA declined from 7.74 ng/mL at baseline to 0.63 ng/mL at 12 months, a 91.9% reduction. No biochemical recurrence was reported during the first year.
- Grade 1–2 genitourinary toxicity was 75.2% at treatment completion, falling to 49.2% at three months, 33.0% at six months, and 38.5% at 12 months. One patient developed grade 3 acute genitourinary toxicity (0.6%), with no persistent grade ≥3 events.
- Grade 1–2 gastrointestinal toxicity was 18.4% at treatment completion and 11.5% at 12 months, with no grade ≥3 gastrointestinal toxicity. Urinary patient-reported outcomes recovered from three months onward, while lower sexual-function scores were concentrated among patients receiving androgen-deprivation therapy.
CLINICAL TAKEAWAY
The registry supports the feasibility of delivering five-fraction prostate SBRT safely across academic and non-academic linac centres using varied motion-management strategies. It adds implementation evidence rather than new efficacy proof, and the 14-month follow-up is inadequate for assessing late genitourinary toxicity or durable biochemical control.