A clinical trial has demonstrated that using Elekta's 1.5T Unity MR-Linac for prostate cancer treatment can significantly preserve erectile function in male patients by enabling more precise radiation delivery that spares critical structures responsible for sexual function.
The preliminary results of the ERECT (EREctile Function Preservation for Prostate Cancer Radiation Therapy) trial were presented at the 2025 European Society for Radiotherapy and Oncology (ESTRO) annual congress in Vienna, Austria. The trial, a sub-study of the MOMENTUM MR-Linac Consortium's platform registry, showed substantially reduced incidence of erectile dysfunction (ED) in patients treated with MR-guided radiotherapy compared to conventional approaches.
Significant Reduction in Erectile Dysfunction Rates
In the single-center, phase 2 trial, researchers from University Medical Center Utrecht (UMC Utrecht) in the Netherlands treated 70 intermediate-risk prostate cancer patients with a radiation dose of 36.25 Gy delivered over five fractions using the Elekta Unity MR-Linac system.
The study found that ED incidence was significantly lower in patients receiving neurovascular-sparing MR-guided radiotherapy compared to a control group that received the same dosage without neurovascular sparing:
- At 6 months: 6% vs. 21% (p = .015)
- At 12 months: 8.5% vs. 38% (p < .001)
- At 18 months: 16% vs. 36% (p = .019)
Patients with neurovascular sparing also maintained higher mean scores on the International Index of Erectile Function-5 (IIEF-5) questionnaire at all time points, indicating better preservation of sexual function.
Advanced Visualization Enables Precision Treatment
According to Dr. Jochem van der Voort van Zyp, radiation oncologist at UMC Utrecht and principal investigator of the trial, the Elekta Unity's high-quality MR imaging capabilities were crucial to the study's success.
"While radiation therapy for prostate cancer has been shown to confer very high cure rates, the close proximity of nerves and blood vessels that support sexual function can mean they receive a radiation dose sufficient to interfere with their function," explained Dr. van der Voort van Zyp. "However, with the enhanced precision of MR-guidance, we gain the confidence to limit – or deescalate – the dose they receive. In short, the prostate gets the therapeutic dose while the erectile tissues receive a much lower dose, thus preserving their function."
The system's pristine MR image quality enabled detailed visualization of not only the prostate but also critical structures needed for erectile function, including the neurovascular bundle, internal pudendal arteries, corpora cavernosa, and penile bulb.
Technology Behind the Improvement
The Elekta Unity MR-Linac is the world's first and only device to combine a high-field MRI with a state-of-the-art linear accelerator. This integration allows clinicians to use MRI to guide radiation delivery to tumor targets while avoiding surrounding structures.
A key advantage of the system is its ability to monitor the position of the target non-invasively during treatment. If the prostate shifts due to bowel movement or bladder filling, treatment can be paused to prevent unnecessary radiation exposure to surrounding normal tissues.
"An obvious way to reduce dose to normal tissues is to 'see what you treat,' and the best way to see the prostate and surrounding tissues is using MR-guidance," noted Dr. John Christodouleas, Senior Vice President of Medical Affairs at Elekta.
Study Design and Patient Characteristics
Eligible patients for the ERECT trial were 18 years or older with histologically proven adenocarcinoma of the prostate that was low-risk or intermediate-risk according to NCCN risk categories. Participants needed to have a domain score of 17 to 25 on the IIEF-5 questionnaire and a Karnofsky performance status of 70 to 100.
The median age of patients in the experimental group was 63 years compared to 68 years in the control group (p < .001). The distribution of International Society of Urological Pathology (ISUP) grades also differed between groups, with 26% vs. 12% having ISUP grade 1 disease and 8.8% vs. 25% having ISUP grade 3 disease in the experimental and control groups, respectively.
Implications for Prostate Cancer Treatment
Prostate cancer is one of the most common cancers in men, and while radiation therapy is highly effective at controlling the disease, treatment-related side effects can significantly impact quality of life. The preservation of sexual function represents an important advancement in maintaining patients' quality of life during and after cancer treatment.
"These results from the ERECT Trial add to a growing evidence base showing that minimizing the radiation dose to the normal tissues surrounding the prostate can improve the quality of life of men with prostate cancer," said Dr. Christodouleas.
The findings suggest that MR-guided radiotherapy using systems like the Elekta Unity MR-Linac could become an important option for prostate cancer patients who wish to maintain sexual function while receiving effective cancer treatment.
Further research and longer follow-up will be needed to confirm the durability of these results and to assess other important outcomes such as relapse-free survival, which was included as a secondary endpoint in the trial along with patient-reported quality of life and acute and late gastrointestinal and genitourinary toxicity.
