Clinical Research Directory

Adaptive Radiation Therapy (ART) Stereotactic Ablative Body Radiotherapy (SABR) for Primary Localized Prostate Cancer

This clinical trial evaluates changes in quality of life after two treatments with near margin-less adaptive radiation therapy (ART) compared to five treatments with standard stereotactic ablative body radiotherapy (SABR) in patients with prostate cancer that has not spread to other parts of the body (localized). ART is a type of radiation therapy that uses information gathered during the treatment cycle to inform, guide, and alter future radiation treatments with respect to location and dose. It may be able to deliver radiation to the site of disease over a shorter time and with smaller margins (less treatment delivered to nearby healthy tissues). SABR is a type of external radiation therapy that uses special equipment to position a patient and precisely deliver radiation to tumors in the body (except the brain). The total dose of radiation is divided into smaller doses given over several days. This type of radiation therapy helps spare normal tissue. Shorter duration near margin-less ART may be just as effective at treating patients with localized prostate cancer but have less quality of life side effects than standard SABR.

Feasibility of MR-Informed Adaptive Marker-less SBRT in Patients With Bilateral Hip Prostheses Undergoing SBRT for Localized Prostate Cancer

Hip replacements and prostate cancer are independently and both together increasing prevalent in the aging population. In the United States, the prevalence of hip prostheses among men was 1.1 million in 20101, with approximately 500,000 hip prostheses performed annually. Bilateral total hip replacement is recommended for patients with osteoarthritis affecting both hip joints. Approximately 10-25% of total hip replacement patients undergo bilateral procedures. Stereotactic body radiotherapy (SBRT) has been widely adopted as an effective treatment for localized prostate cancer, offering high precision and reduced treatment time due to conventionally fractionated radiotherapy without increasing toxicity or comprising oncological outcomes. Therefore, the use of SBRT for treatment of localized prostate cancer has significantly increased. A cohort study using data from 302 035 patients in the National Cancer Database showed that use of SBRT for prostate cancer increased from 0.2% in 2004 to 12.4% in 2020 in the United States. However, both CT and MR-guided SBRT present unique challenges for patients with prostate cancer and bilateral hip prostheses. Metallic implants, such as hip prostheses, produce artifacts and magnetic susceptibility issues that can obscure MR imaging near the prosthetic sites, potentially complicating target contouring and planning. Given the close proximity of the prostate gland to the pelvis, which houses the hip joints, patients with bilateral hip prostheses may have significant imaging artifacts that could impair MR-guided radiotherapy quality. CT-based SBRT is less affected by metallic artifacts, but it lacks the soft-tissue resolution needed for precise prostate and OAR delineation, a gap MR imaging is uniquely positioned to fill. Low-field MRI systems are less prone to susceptibility artifacts, including those originating from metallic implants. As a result, signal loss and distortion are expected to occur only in the immediate vicinity of the implant, making these systems particularly advantageous for imaging patients with hip implants. A prospective study quantitatively and qualitatively compared the magnitude of metal total hip arthroplasty-induced imaging artifacts in vivo between 1.5T (i.e. high-field) and 0.55T (low-field) MRI in 15 patients. Qualitative artifact magnitude was on average rated as moderate to small on 0.55T and as large to moderate on 1.5T by 2 fellowship-trained musculoskeletal radiologists. In addition, metal artifacts' areas and diameters were smaller on 0.55T when compared with 1.5T MRI for all sequences (each p\>0.016). Given the limitations of current imaging systems, the investigators propose a more flexible solution: a two-room system comprising a low-field MRI scanner for optimal image quality and a C-arm linear accelerator for rapid treatment delivery. Patient transfer between the MR device and the linear accelerator will be performed with a shuttle system which uses an air-bearing patient platform for both procedures. This setup would allow for high-quality imaging with reduced artifacts while ensuring efficient treatment times, addressing the current gap in SBRT for patients with bilateral hip prostheses. This shuttle system is MR-compatible and uses an air-bearing technology that allows the patient to be effortlessly moved by a transfer sled from MR scanner couch to linac without any movement on their part as it utilises the same patient platform with treatment using supports, immobilization devices and stereotactic tools for both procedures. This means that the patient is scanned and treated in the same position, minimising the risk of translational and/or rotational positional changes during transfer between both devices. Thus, maximum use of image-based planning data is possible. By integrating a low-field MRI scanner with a dedicated treatment delivery system, the investigators can overcome existing limitations and improve treatment precision for this growing patient population.

Image-Guidance and Online Adaptation With Stereotactic Body Radiation Therapy for the Treatment of Localized Prostate Cancer, MANTICORE Trial

This clinical trial studies the side effects of image-guidance and online adaptation with stereotactic body radiation therapy (SBRT) for the treatment of patients with prostate adenocarcinoma that has not spread to other parts of the body (localized). Image-guided SBRT is a standard treatment for localized prostate cancer. This treatment uses imaging of the cancer within the body to define and localize the area to be treated with the radiation. Imaging can be obtained using either computed tomography (CT), magnetic resonance imaging (MRI), or a combination of the two. Typically, with SBRT, a radiation plan is developed based on the CT or MRI images obtained before treatment begins and adjustments are not made to the plan during treatment. However, anatomy can be different from day-to-day which may cause radiation to be delivered to the normal surrounding structures and possibly more side effects. During image-guided SBRT with online adaptation, the initial radiation plan is designed similarly; however, when the patient presents for radiation, the attending radiation oncologist, a dosimetrist, and a medical physicist "re-optimize" the radiation plan using the current anatomy of the day, meaning the changes in bladder and prostate size/shape are taken into account. The initial plan and the re-optimized plan are then compared, and the plan that has the optimal balance between delivering a tumor killing dose of radiation and minimizing radiation dose to normal surrounding structures is delivered. Image-guidance and online adaptation with SBRT may lower side effects and be a safer way to treat localized prostate adenocarcinoma.

Early Magnetic Resonance Imaging Response of the Dominant Intraprostatic Lesion After Online Adaptive Stereotactic Body Radiotherapy for Localized Prostate Cancer and Correlation With Prostate Specific Antigen Response

The aim of this phase II study is to determine the early multiparametric magnetic resonance imaging response of the dominant intraprostatic lesion and correlate these findings with prostate specific antigen response in patients with intermediate to (very) high risk localized prostate cancer treated with online adaptive stereotactic radiotherapy without intraprostatic fiducial markers.

Computed Tomography-Guided Stereotactic Body Radiation Therapy With Intrafraction Motion Monitoring for the Treatment of Localized Prostate Cancer, ILLUSION Trial

This clinical trial studies the side effects of computed tomography (CT)-guided stereotactic body radiation therapy (SBRT) with intrafraction motion monitoring and to see how well it works in treating patients with prostate cancer that has not spread to other parts of the body (localized). In CT-guided SBRT, x-ray-based imaging and cone-beam CTs are used to define and localize the area to be treated with SBRT. SBRT is a type of external radiation therapy that uses special equipment to position a patient and precisely deliver radiation to tumors in the body (except the brain). The total dose of radiation is divided into smaller doses given over several days. This type of radiation therapy helps spare normal tissue. A recent randomized trial showed that while SBRT is associated with less urinary incontinence and erectile dysfunction than complete surgical removal of the prostate, there are more urinary irritative side effects and more bowel side effects than with surgery. One source of uncertainty in SBRT that may contribute to genitourinary (GU) and gastrointestinal (GI) side effects is the necessity of treating a "margin" of volume around the prostate to account for its movement during SBRT. Intrafraction motion monitoring is any technique or system designed to track the movement of the body and target during fractions of external beam radiation to keep the beam on target. This allows for the patient to be repositioned, if needed, to ensure delivery of the SBRT to only the planned treatment area. CT-guided SBRT with intrafraction motion monitoring may lower GU and GI side effects by allowing tighter margins, as has been demonstrated with magnetic resonance imaging (MRI)-guided SBRT.