Session Item

Poster (digital)
Metastasis-Directed Therapy with Cyberknife for Oligometastatic Prostate Cancer  
Sebastian Exner, Germany


Metastasis-Directed Therapy with Cyberknife for Oligometastatic Prostate Cancer  

Sebastian Exner1, Fabian Fehlauer1, Saul Esteve Grau1

1Strahlenzentrum Hamburg, Radiotherapy, Hamburg, Germany

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Purpose or Objective

To investigate the effects of Cyberknife-stereotactic radiosurgery (CK-SRS) for oligometastatic prostate cancer patients.  

Material and Methods

We retrospectively identified all patients with oligometastatic prostate cancer (≤ 5 metastasis in ≤ 3 organs) treated with CK-SRS at our institution since January 2012 to September 2021 and analyzed data of primary diseases, multimodality treatments and local therapy effect based on PSA testing and treatment safety. Patients were split in 3 groups depending on the time they received androgen deprivation therapy, Group A: never, Group B: after radiosurgery, Group C: before radiosurgery.   

All patients were treated with Cyberknife, that consist of a lightweight linear accelerator mounted on a robotic system, giving the ability to deliver highly non-coplanar dose distributions. It differs from conventional SBRT modalities with its real-time image-guidance system which allows for more accurate radiation delivery.  


The study population of 82 patients was between 48 and 80 years old (median 64 years) and 193  metastases were treated. The mean follow-up time was 7.47 months. The prostate-specific antigen level was before radiosurgery between 0.27 and 109 ng/ml (Average 14.45 ng/ml). The average planning target volume (PTV) was 43.94 (range: 0.19–695.34) cm3. Multiple fractions were applied in 46.6% of the lesions with a median prescription dose of 24 Gy (range: 5-15). 

 The Gleason score was between 6 and 9 (median 7). The diagnostic imaging used were PSMA-PET-CT (95.3%), CT (86.5%) and MRI (56.9%). The group with the highest overall survival (OS) was Group B (97.92 months), followed by Group C and A (86.16 and 82.56 months respectively). The average OS resulted in 88.8 months.  Also, the ADT- Free Survival measured in Group B, was of 3.95 years. 

 There were no major adverse effects during or after radiosurgery.   


For oligometastatic prostate cancer, the metastasis Directed therapy (MDT) delivered using Cyberknife-stereotactic radiosurgery is a safe and efficient option with excellent local control rates and Overall-survival.   We recommend testing MDT in larger prospective, multicenter, randomized trials.