Brain, Spine, Prostate, Liver & Oligometastases: Here are the research highlights concerning CyberKnife treatment for these types of cancer from ESTRO 2025 – The European Society For Radiotherapy and Oncology ~ The theme for ESTRO 2025 was “Transformative Innovation Through Partnership, emphasizing the importance of collaboration and partnership to push the boundaries of radiation oncology and multidisciplinary cancer care. The program featured interactive sessions, panel discussions, and joint sessions with partner associations, focusing on breakthrough research and innovation. The congress aimed to connect the radiotherapy community, highlight top-level scientific work, and foster collaboration between all stakeholders.
At Accuray, the manufacturer of CyberKnife we introduced a powerful theme of our own: “Distinct in Every Way,” with three core pillars, Distinct by Outcomes, Distinct by Design and Distinct by Expertise. This theme underscores our unwavering commitment to excellence in radiotherapy; with a goal to ensure more patients receive precise and effective radiotherapy treatments.
Together, these themes represent a unified approach to advancing cancer treatment through innovative and collaborative efforts, highlighting the importance of working together to achieve superior outcomes in radiation oncology.
In this blog we take immense pride in showcasing some of the research presented at ESTRO 2025 by radiation oncologists, medical physicists, and therapeutic radiographers who use the Accuray CyberKnife® System. Their dedication to advancing the field of radiotherapy exemplifies the transformative impact of our innovative technologies.
CyberKnife® System Research Highlights
Brain
Abstracts that focused on intracranial cases treated with the CyberKnife® System included brain metastases, glioblastoma and pituitary adenoma. One study found the CyberKnife System offered an effective treatment option for patients with primary tumors that rarely metastasize to the brain. A median dose of 20 Gy in a single fraction was delivered to 47 patients and a median overall survival (OS) of 89.9 months was recorded, demonstrating high local control rates.
Another study reviewed 42 patients with two or more stereotactic radiosurgery (SRS) treatments to new brain metastasizes, finding acceptable rates of brain progression free survival and toxicity.
A center in Spain treated 30 patients with pituitary adenoma post surgery with the CyberKnife System using 24-25 Gy in 3-5 fractions. With a median follow up of 26 months, no late toxicity was observed and all patients showed a radiological response or stability.
A study conducted in Poland examined 78 patients diagnosed with glioblastoma, who required re-irradiation following an initial total dose of 60 Gy. These patients received an additional 10-16 Gy administered in 2 fractions, contingent upon the tumor’s size and location. The progression-free survival for this cohort ranged from 3 to 24 months. The study concluded that stereotactic radiation therapy utilizing the CyberKnife System offered a valuable treatment option in these patients, offering good efficacy and low toxicities.
Spine
Spine stereotactic body radiotherapy (SBRT) is becoming more widely available and there is increasing evidence for its use. A study of 119 patients treated with SBRT to the spine evaluated doses delivered to the spinal cord and the rate of radiation myelopathy. They found that no radiation myelopathy was seen in any patient at 18 months post SBRT. The use of intrafraction tracking with Synchrony® helped to give confidence that the dose was delivered as planned.
Another retrospective study of 91 patients treated with spinal SBRT also found excellent local control with a low risk of vertebral compression fracture (VCF). An increased risk of VCF was associated in patients >70 years.
A study conducted in Spain examined 61 patients who received spinal SBRT treatment. The study concluded that SBRT administered using the CyberKnife System was effective for managing spine metastases. They found the risk of VCF came at a higher risk in patients treated with a single fraction.
Prostate
Many studies continue to demonstrate the benefits of SBRT to patients with low-intermediate and high-risk prostate cancer. Here are some highlights:
A retrospective study compared the CyberKnife System to low dose rate brachytherapy (LDR-BT). They reviewed 226 low- and intermediate-risk prostate cancer patients (119n = CyberKnife System and 107n = LDR-BT). Local relapse free survival was found to be significantly higher in the CyberKnife System group. Although more acute gastrointestinal (GI) side effects there was no significant difference when reviewing the late GI side effects. The 6-year outcome with the CyberKnife System were found to be similar or even better than with LDR-BT.
Preliminary results of the PRO-FAST study were presented. This is prospective single-arm trial of urethral sparing HDR-like SBRT for prostate cancer patients. The first 12 patients were treated, including high-risk, unfavorable and favorable intermediate risk patients. No grade 3 toxicity was recorded in the first 12 patients which has allowed the study to continue recruiting more patients for this type of treatment. This treatment greatly benefits patients who have long distances to travel for treatment, allowing them to have treatment is just one day.
Another prospective observational trial called PRO-SPEED evaluated acute and late genitourinary and gastrointestinal toxicities as well as biochemical and clinical outcomes in patients with localized prostate cancer treated with ultra-hypofractionated SBRT with a simultaneous integrated boost to the dominant intraprostatic lesions using the CyberKnife System. Thirty patients completed treatment receiving 36.25 Gy to the prostate and 40 Gy to the DIL over five fractions. Preliminary data to data demonstrated that this treatment was effective with low rates of GU and GI toxicities, excellent early biochemical and clinical control.
A retrospective planning study compared radiation dose and treatment efficiency between the InciseTM Multileaf Collimator (MLC) and the Iris collimator with the CyberKnife System in prostate cancer patients. The preliminary results suggested advantages with the InCise MLC over the Iris collimator in terms of beam on time and monitor units. Dosimetric parameters were mainly comparable but further investigation is required to determine if the Iris collimator can offer superior dose minimization to OAR in certain patients. This study gives insights on the ideal collimator to use depending on specific patient cases.
Read the press release to learn more on impactful prostate cancer studies
Liver
A retrospective study assessed local control and recurrence in patients receiving hepatic SBRT in more than 4 fractions due to dosimetric limits. Thirty-three patients, unsuitable for 3-4 fractions due to nearby OARs, were treated for hepatocellular carcinoma or liver metastases in more than 4 fractions. Despite dose reductions to protect OARs, SBRT achieved satisfactory local control with low toxicity. Prospective data is needed to confirm these findings.
A study was conducted to assess the treatment outcomes for patients with malignant liver lesions who were treated using the CyberKnife System. The study included forty-one patients with 1-5 lesions, ranging in size from 0.8 to 6.5 cm. Treatment protocols varied from 3 to 12 fractions, with a total mean dose of 50.5 Gy. The OS rates at 1, 2, and 3 years were 92.5%, 88.9%, and 69%, respectively. With a mean follow-up period of 32.6 months, no late toxicities were observed. The authors concluded that robotic SBRT for liver lesions is an effective local treatment method, demonstrating high rates of local control and minimal acute toxicities.
Oligometastases
A phase-II study evaluated 52 patients with abdominal lymph node metastases undergoing CT-guided, online adaptive SBRT to increase iso-toxic dose to the target. For each patient, three plans were created using pre-treatment CT scans: Standard of care plan, adaptive plan with OAR contours from a diagnostic CT, and an adaptive plan based on the planning CT. After a pre-fraction in-room CT scan, the radiation technologist selected the plan with the highest target coverage without exceeding OAR constraints. An adaptive plan was chosen in 58% of fractions and 78% of patients were treated with at least one adaptive plan; resulting in a significantly higher given GTV Dmean compared to the planned dose. The authors concluded that this workflow enabled a dose increase to the target and offers a chance of better oncological outcomes.
A retrospective study analyzed outcomes and safety of robotic SBRT performed at a single institution for oligometastatic disease from gynecological tumors. Fifty-four patients were included in the study. A median dose of 40 Gy in 1-8 fractions was prescribed. Oligometastases were located in the lung, liver, lymph node, bone and brain. No acute grade 3 or higher toxicities were reported. The authors found using higher doses than in the MITO retrospective trials, they observed a high rate of local complete response and local relapse free survival. Patients with a complete response after SBRT demonstrated a significantly higher disease free survival compared to those with stable/partial response or progressive disease.