StereoBed trial to compare radiotherapy schedules after prostate surgery

The multicenter StereoBed trial will randomize 284 patients with persistent or rising prostate-specific antigen levels after radical prostatectomy to compare standard-of-care radiotherapy schedules with a five-fraction stereotactic body radiotherapy schedule. Its two co-primary endpoints are changes from baseline in urinary and bowel patient-reported outcomes at two years. The study protocol describes planned methods and objectives; it does not report comparative safety, efficacy or quality-of-life results.

Salvage radiotherapy is a well-established treatment for biochemical recurrence after the surgical removal of the prostate. Stereotactic body radiotherapy, abbreviated SBRT, may offer a shorter treatment duration and favorable radiobiological characteristics, but evidence in the postoperative setting remains limited. The investigators say StereoBed is among the first multicenter randomized phase II/III trials designed to assess whether SBRT increases gastrointestinal or genitourinary symptoms compared with standard-of-care fractionation at the two-year time point.

The trial will therefore evaluate symptom outcomes as its central question while also collecting data on toxicity, disease control, survival, quality of life and costs. Participants will be assigned in a 1:1 ratio to one of two arms. Arm A will receive normofractionated or mildly hypofractionated radiotherapy, specified as 64–70 Gy in 32–35 fractions or 52.5 Gy in 20 fractions.

Arm B will receive SBRT delivered as 32 Gy in five fractions. Randomization will be stratified by study center and by the investigator’s treatment choices concerning standard-of-care androgen deprivation therapy, listed as six months, and whole-pelvis radiotherapy. These stratification factors mean that the comparison will account for differences between participating centers and for the investigators’ planned use of adjunctive treatments.

The primary assessment will use the 26-item Expanded Prostate Cancer Index Composite, or EPIC-26. The two co-primary endpoints are the two-year changes from baseline in its urinary and bowel domains. Secondary patient-reported outcomes include all EPIC-26 domains, scores from the International Prostate Symptom Score and the EQ-5D-5L instrument, measured for up to five years.

The protocol also specifies biochemical progression-free survival, distant metastasis-free survival, local and regional control, overall survival and an analysis of the lymphocyte nadir relative to baseline as additional endpoints. Researchers will also conduct a cost-utility analysis based on EQ-5D-5L scores and treatment-related transportation costs. Because StereoBed is a protocol, the relative effects of the five-fraction and standard schedules remain unknown until the randomized comparison produces results; the stated primary test concerns two-year urinary and bowel symptom changes rather than a direct comparison of treatment convenience or disease-control efficacy.

Subject of Research: Randomized comparison of stereotactic and standard salvage radiotherapy schedules for biochemical recurrence after radical prostatectomy

Article Title: StereoBed – salvage stereotactic body radiotherapy of the prostate bed for biochemical recurrence after radical prostatectomy: study protocol for a randomized phase II/III trial

Article References: Jullian, N., De Bruyn, P., Poeta, S., Kristanto, P., Penninckx, S., Dirix, P., Draulans, C., Nguyen, P., Meersschout, S., Bulens, P., Sundahl, N., Vandermeulen, A., vandenbergh, L., Palumbo, S., Engels, B., Berghen, C., Vanneste, B., Ost, P., & Van den Begin, R. (2026). StereoBed – salvage stereotactic body radiotherapy of the prostate bed for biochemical recurrence after radical prostatectomy: study protocol for a randomized phase II/III trial. BMC Cancer. https://doi.org/10.1186/s12885-026-16874-7

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DOI: 10.1186/s12885-026-16874-7

Keywords: StereoBed, prostate cancer, biochemical recurrence, radical prostatectomy, salvage radiotherapy, stereotactic body radiotherapy, hypofractionation, patient-reported outcomes, randomized trial, quality of life, salvage, stereotactic