MRI-assisted radiosurgery and brachytherapy for prostate cancer treatment
June 25, 2021
Medically Reviewed | Last reviewed by an MD Anderson Cancer Center medical professional on June 25, 2021
For many years, brachytherapy has been used to treat low-risk, intermediate-risk, and high-risk prostate cancer. But more recently, doctors have been using a more advanced form of brachytherapy called MRI-assisted radiosurgery (MARS), which enables them to deliver the radiation directly to the tumor while protecting the healthy tissues nearby.
We discussed the benefits of MRI-Assisted Radiosurgery used with brachytherapy treatment with Steven Frank, M.D., who developed the Food and Drug Administration-approved positive-contrast MRI marker technology at MD Anderson for prostate cancer treatment.
What is brachytherapy?
Brachytherapy is a type of internal radiation therapy where tiny radioactive seeds are implanted in the body to destroy cancer cells. These seeds are about the size of a grain of rice.
When treating prostate cancer with brachytherapy, the implant is placed directly in the prostate as close to the tumor as possible. This allows us to deliver high doses of radiation directly to the tumor while limiting radiation exposure to healthy tissue.
What is MRI-assisted radiosurgery (MARS)?
MARS is currently the most advanced form of brachytherapy. This modern technique, used for treating prostate cancer, provides more precise delivery of radiation and fewer radiation-related side effects.
MRI-assisted radiosurgery destroys the tumor within the prostate. Radiosurgery is a very precise form of therapeutic radiation therapy where the prostate is not removed.
Before MARS was developed, brachytherapy was done using CT scans and ultrasounds for imaging. However, because the implanted radioactive seeds are difficult to view with conventional imaging, it’s harder to ensure precise placement of the seed, which can influence the effectiveness of the therapy.
So, in 2009, a permanent implantable positive-contrast MRI marker was created for use in prostate brachytherapy to improve quality assurance of the treatment. This marker enabled the use of MRI in treatment planning, delivery, and post-implant assessment and the development of MRI-assisted radiosurgery, also known as MARS.
Now, with the use of MRI to assist in placing seeds in prostate cancer patients, our experts can better visualize the tumor during treatment so we can avoid radiation to surrounding healthy tissues near the prostate.
What is the difference between low-dose and high-dose rate brachytherapy?
Depending on the complexity of the tumor, brachytherapy treatment uses either:
- low-dose rate radioactive seeds, which are implanted permanently, or
- high-dose rate radioactive seeds, which are temporary.
Both are done as outpatient procedures, with little downtime for patients.
How does MARS work?
MRI is used at every step of the quality assurance process from diagnosis, treatment simulation, contouring, treatment planning, treatment delivery, and assessment afterward. MRI markers allow physicians to accurately locate the implanted seeds within the prostate. This helps make the delivery of the internal radiation treatment very precise.
Which cancer patients are most likely to benefit from MARS brachytherapy?
MARS brachytherapy has been used to treat low-risk, intermediate-risk, and high-risk localized prostate cancer for several years. Doctors will perform a physical exam and imaging exam to evaluate current urinary symptoms and determine if this is the best treatment approach for each patient.
What does the treatment regimen look like for patients who receive MARS?
Patients with early-stage disease are treated with MARS brachytherapy alone to deliver precisely targeted radiation to the tumor. For patients with more advanced-stage disease, the MARS implant takes place after the patient completes four weeks of external beam radiation treatment with either proton therapy or intensity-modulated radiation therapy in combination with hormone therapy. This is done to increase the radiation dose to the tumor, with the goal of reducing the risk of the disease progressing.
What are the benefits of MARS?
By using MRI at each step of the MARS treatment process, our experts can better see the tumor and the surrounding organs to ensure very accurate placement of the seeds. This will help to optimize cure while minimizing both acute and long-term side effects after treatment. Without MARS, the external urethral sphincter cannot be seen with standard CT or ultrasound imaging.
What are the side effects associated with MARS?
Side effects from MARS are minimal. Most patients return to normal activities the day after the procedure. After treatment, patients can return to normal sexual activity. Incontinence is rare, but some patients may experience temporary urinary side effects. These include burning, frequent or urgent need to urinate. These side effects can be managed with medication and typically resolve a few months after treatment.
Disclosure: Steven Frank, M.D., and MD Anderson Cancer Center licensed IP related to MARS to C4 Imaging, LLC, and Dr. Frank holds equity in the company and currently serves as the Chairman of their board of directors.
Request an appointment at MD Anderson online or by calling 1-877-632-6789.
For many years, brachytherapy has been used to treat low-risk, intermediate-risk and high-risk prostate cancer. But more recently, doctors have been using a more advanced form of brachytherapy called MRI-assisted radiosurgery (MARS), which enables them to deliver the radiation directly to the tumor while protecting the healthy tissues nearby.
We discussed the benefits of MRI-Assisted Radiosurgery used with brachytherapy treatment with Steven Frank, M.D., who developed the FDA-approved positive contrast MRI marker technology at MD Anderson for prostate cancer treatment.
What is brachytherapy?
Brachytherapy is a type of internal radiation therapy where tiny radioactive seeds are implanted in the body to destroy cancer cells. These seeds are about the size of a grain of rice.
When using brachytherapy to treat prostate cancer, the implant is placed directly into the prostate as close to the tumor as possible. This allows us to deliver high doses of radiation directly to the patient’s tumor while limiting radiation exposure to healthy tissue.
What is MRI-assisted radiosurgery (MARS)?
MARS is the most advanced form of brachytherapy. This modern technique used for treating prostate cancer, provides a more precise delivery of radiation and a reduction of radiation-related side-effects.
MRI-assisted radiosurgery is an ablation of the prostate. Radiosurgery is a very precise form of therapeutic radiology where the prostate is not removed.
Before MARS was developed, brachytherapy was done using CT scans and ultrasounds. However, because the implanted radioactive seeds are difficult to view through conventional imaging, it’s harder to ensure precise placement of the seed which can impact the therapy’s effectiveness.
So, in 2009, a permanent implantable positive contrast MRI marker was created for use in prostate brachytherapy to improve quality assurance of the treatment. This enabled the use of MRI in treatment planning, delivery, and post-implant assessment and the development of MRI-assisted radiosurgery, also known as MARS.
Now with the use of MRI to assist in the seed placement in prostate cancer patients, our experts have better visualization of the tumor during treatment so we can avoid surrounding healthy tissues near the prostate.
What is the difference between low-dose and high-dose rate brachytherapy?
Depending on the complexity of the tumor, brachytherapy treatment uses either a low-dose or high-dose rate radioactive seed. Both are done as outpatient procedures so that little downtime is required for patients.
In low-dose rate brachytherapy, the seed is implanted permanently into a patient’s body. After implant, patients are treated with a low dose of radiation for hours at a time. This is now a standard option for the curative treatment of prostate cancer.
With high-dose rate brachytherapy, the seed is implanted into the prostate temporarily. The patient is then treated with a higher dose of radiation delivered to the tumor in a short burst. This lasts only a few minutes and may be repeated several times over one or more weeks.
How does MARS work?
MRI markers allow physicians to accurately locate the implanted seeds within the prostate. This helps make the delivery of the internal radiation treatment very precise. A radioactive source is then placed inside the applicator and irradiates the immediate area of the cancer before being removed.
Which cancer patients are most likely to benefit from MARS brachytherapy?
Brachytherapy has been used to treat low-risk, intermediate-risk and high-risk prostate cancer for several years. For a patient to qualify for this treatment, the cancer cannot have spread significantly outside the prostate. Doctors will perform a physical exam and imaging exam to evaluate current urinary symptoms and determine if this is the best treatment approach for the patient.
What does the treatment regimen look like for patients who receive MARS?
Patients with low-risk and intermediate-risk disease are treated with MARS brachytherapy alone, while patients with advanced-stage disease receive external beam radiation therapy such as proton therapy for four weeks. Then, two weeks after they’ve completed external radiation, patients receive a radioactive seed implant through MRI-assisted radiosurgery.
The MARS implant is given after the patient completes external beam radiation treatment. This is done to increase the radiation dose to the tumor. This also decreases the risk of the disease progressing. When patients are not candidates for proton therapy or have a more advanced disease, MARS can be used as a precise targeted radiation to the tumor.
What are the benefits of MARS?
MARS ensures the precise placement of the radioactive seed during the procedure. By using MRI during the treatment process, our experts can better see the surrounding organs to provide very accurate placement of the seed. This also minimizes side effects for treatment of both early and advanced stage prostate cancer. Without MARS, the urethra is not visible using a CT scan or ultrasound.
What are the side effects associated with MARS?
Side effects from MARS are minimal and most patients return to normal activities the day after the procedure. After treatment, patients can return to normal sexual activity. Incontinence is rare, but some patients may experience temporary urinary side effects. These include burning, frequent or urgent need of urination. These side effects can be managed with medication and typically resolve a few months after treatment.
Disclosure: Steven Frank, M.D., and MD Anderson Cancer Center licensed IP related to MARS to C4 Imaging, LLC, and Dr. Frank holds equity in the company and currently serves as the Chairman of their board of directors.
Request an appointment at MD Anderson online or by calling 1-877-632-6789.
Topics
BrachytherapyWith MARS brachytherapy, we can limit uncertainty, provide optimal quality assurance and minimize side effects.
Steven Frank, M.D.
Physician