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high relevance prostate sbrt consensus-guidelines

ESTRO defined minimum standards for prostate SBRT implementation

ESTRO recommends prostate SBRT for selected intermediate-risk disease with MRI-based contouring, rigorous quality assurance, and daily image guidance.

RadOncToday · ·1 min read

KEY POINTS

  • The recommendations were developed by 15 European experts—11 radiation oncologists, three medical physicists, and one RTT—from nine countries. A two-round Delphi process addressed ten areas of controversy, with consensus defined as at least 75% agreement and strong consensus as at least 90%.
  • Strong consensus supported prostate SBRT as standard treatment outside trials for ISUP grade groups 2–3, cT1c–cT2c disease, and PSA below 20 ng/mL. Support was limited for ISUP 4, cT3a, or PSA 20–40 ng/mL and absent for more advanced categories.
  • No consensus was reached on a maximum prostate volume. Among experts using a limit, the median threshold was 90 cm³ with a range of 70–150 cm³. A maximum baseline IPSS was supported by 85%, with a median suggested threshold of 17.
  • All voting experts recommended restricting SBRT after TURP, HoLEP, or other benign-prostatic-hyperplasia surgery to selected patients after an adequate recovery interval. The median recommended waiting period was six months, ranging from two to 12 months.
  • The principal standard regimen is 36.25 Gy in five fractions to 95% of the PTV, with 40 Gy to 95% of the prostate CTV, based on PACE-B. 42.7 Gy in seven fractions is an accepted alternative; an every-other-day or similarly protracted schedule is considered reasonable to reduce low-grade toxicity.
  • Planning MRI with T2-weighted imaging and registration to simulation CT is strongly recommended. Daily pretreatment CBCT soft-tissue matching or fiducial-based imaging is the minimum standard when using margins of at least 5 mm; most experts favoured adding intrafraction monitoring when using smaller margins, but formal consensus was not reached.
  • Routine rectal-spacer use was rejected by 85% of experts because the overall risk–benefit balance remains uncertain. Patient-specific QA is recommended, generally using tighter gamma criteria such as 2%/2 mm or stricter, with a passing rate of at least 90%.

CLINICAL TAKEAWAY

The consensus provides a practical baseline for departments implementing prostate SBRT and clarifies which elements are mandatory versus optional. Evidence is strongest for intermediate-risk, organ-confined disease; high-risk treatment, very small margins, focal escalation, and routine spacer use require more selective application.

SOURCE

Radiotherapy and Oncology