Robotic stereotactic body radiotherapy for localized prostate cancer: final analysis of the German HYPOSTAT trial

David Krug*, Detlef Imhoff, Alfred Haidenberger, Nicole Heßler, Jane Schäfer, Stefan Huttenlocher, Georgios Chatzikonstantinou, Christoph Fürweger, Ulla Ramm, Inke R. König, Felix Chun, Michael Staehler, Claus Rödel, Alexander Muacevic, Reinhard Vonthein, Jürgen Dunst, Oliver Blanck

*Corresponding author for this work


Purpose: We report results of the first German prospective multicenter single-arm phase II trial (ARO 2013-06; NCT02635256) of hypofractionated robotic stereotactic body radiotherapy (SBRT) for patients with localized prostate cancer (HYPOSTAT). Methods: Patients eligible for the HYPOSTAT study had localized prostate cancer (cT1‑3 cN0 cM0), Gleason score ≤ 7, prostate-specific antigen (PSA) ≤ 15 ng/ml, prostate volume ≤ 80 cm3, and an International Prostate Symptom Score (IPSS) ≤ 12. Initially, inclusion was limited to patients ≥ 75 years or patients 70–74 years with additional risk factors. The trial protocol was later amended to allow for enrolment of patients aged ≥ 60 years. The treatment consisted of 35 Gy delivered in 5 fractions to the prostate and for intermediate- or high-risk patients, also to the proximal seminal vesicles using the CyberKnife system (Accuray Inc., Sunnyvale, CA, USA). Primary endpoint was the rate of treatment-related gastrointestinal or genitourinary grade ≥ 2 toxicity based on the RTOG scale 12–15 months after treatment. Secondary endpoints were acute toxicity, late toxicity, urinary function, quality of life, and PSA response. Results: From July 2016 through December 2018, 85 eligible patients were enrolled and received treatment, of whom 83 could be evaluated regarding the primary endpoint. Patients mostly had intermediate-risk disease with a median PSA value of 7.97 ng/ml and Gleason score of 7a and 7b in 43.5% and 25.9% of patients, respectively. At the final follow-up 12–15 months after treatment, no patient suffered from treatment-related gastrointestinal or genitourinary grade ≥ 2 toxicity. Acute toxicity was mostly mild, with three grade 3 events, and the cumulative rate of grade ≥ 2 genitourinary toxicity was 8.4% (95% CI 4.1–16.4%). There were no major changes in urinary function or quality of life. The median PSA value dropped to 1.18 ng/ml 12–15 months after treatment. There was one patient who developed distant metastases. Conclusion: Robotic SBRT with 35 Gy in 5 fractions was associated with a favorable short-term toxicity profile. Recruitment for the HYPOSTAT‑2 trial (ARO-2018‑4; NCT03795337), which further analyses the late toxicity of this regimen with a planned sample size of 500 patients, is ongoing.

Original languageEnglish
JournalStrahlentherapie und Onkologie
Issue number6
Pages (from-to)565-573
Number of pages9
Publication statusPublished - 06.2023

Research Areas and Centers

  • Research Area: Luebeck Integrated Oncology Network (LION)
  • Centers: University Cancer Center Schleswig-Holstein (UCCSH)
  • Academic Focus: Biomedical Engineering

DFG Research Classification Scheme

  • 205-30 Radiology, Nuclear Medicine, Radiation Therapy and Radiobiology
  • 205-23 Reproductive Medicine, Urology
  • 205-32 Medical Physics, Biomedical Engineering
  • 407-01 Automation, Control Systems, Robotics, Mechatronics, Cyber Physical Systems

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