Men who are diagnosed with prostate cancer are placed into "risk groups" based on a variety of features, including:
-Their initial prostate specific antigen (PSA) laboratory values
-What the doctor has felt on a digital rectal examination
-The Gleason score given to their prostate cancer on review of the biopsy samples
-The number of cores that are positive and the number of cores that are negative on the biopsy samples
More information about the general basics of prostate cancer diagnosis can be found at the following patient-friendly websites
Traditionally, prostate cancer radiotherapy (RT) has been delivered over the course of multiple treatment sessions with a low dose per treatment session. In order to deliver the total dose needed to eradicate prostate cancer, up to 45 treatments were needed, which translates to nine weeks of daily treatments (Monday through Friday). It has since become appreciated that prostate cancer appears to be uniquely sensitive to a higher dose per treatment session, such that prostate cancer could be eradicated in a much shorter amount of time with significantly fewer treatments. Various ways of doing this have been explored. Among them, stereotactic body radiotherapy (SBRT), also known as stereotactic ablative radiotherapy, is a radiation therapy technique that allows the prostate radiotherapy course to be condensed to just five treatment sessions. With SBRT, advanced treatment delivery technologies and radiation planning parameters are used to deliver higher doses per day in a safe and effective manner.
SBRT is now supported by high level evidence as a safe and effective treatment for low and intermediate risk prostate cancer. The UCLA SBRT Prostate Cancer program is led by Dr. Amar Kishan and Dr. Michael Steinberg.
The first patient to be treated with modern prostate SBRT was treated in December 2000. Since then, a large amount of data and evidence have amassed demonstrating the safety and efficacy of SBRT. UCLA investigators have played a leading role in accumulating and publishing these data. To date, the best data available to support SBRT for prostate cancer are:
(a) A study led by Dr. Amar Kishan that compiled the outcomes of 2142 men treated with SBRT between 2000-2012, showing low rates of toxicity and high efficacy with a median follow-up of nearly 7 years. The article can be found here: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2723641
(b) The HYPO-RT-PC randomized trial, which directly compared conventional radiation (39 treatments) against a high-dose-per-day treatment across seven sessions in 1200 Swedish men. Importantly, this trial used older radiation planning techniques and did not deliver modern SBRT. Regardless, the efficacy and long-term side effects were equivalent in both arms of the trial. The article can be found here: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(19)31131-6/fulltext
(c) The PACE-B randomized trial, which directly compared modern, longer course radiation (20 to 39 treatments) against modern SBRT in 874 men in the United Kingdom. No differences in short term side effects were found. The article can be found here:
All of these trials included men with low and intermediate risk prostate cancer. As a result of these data, the National Comprehensive Cancer Network now supports SBRT as a standard option in these patients. Many of the ongoing studies evaluating SBRT, such as the national NRG GU-005 trials, are actually designed to show that SBRT is in fact superior to a longer course of radiation (no longer directly questioning the efficacy or safety of the treatment).
For high-risk prostate cancer, studies are ongoing. The National Comprehensive Cancer Network does allow for SBRT to be used for higher-risk disease if other forms of radiation are impractical, and otherwise suggests enrollment on a clinical trial if SBRT is being used for high-risk disease. UCLA is leading the largest of these trials and is spearheading an international consortium effort to study SBRT for high-risk disease.
Your radiation oncologist at UCLA will review all of the treatment options with you, comparing the pros and cons of each in great detail. Often, there will be several equally good options, and together with your doctors you will be guided through the decision making process in order to arrive at a treatment that is the most appropriate for you and you feel most comfortable with.
All patients are eligible for prostate SBRT. UCLA has clinical protocols specifically designed for low/intermediate risk patients as well as high risk patients.
There are many good reasons to consider and choose SBRT over the other potential options, including:
SBRT consists of a much shorter course of radiotherapy than the conventional approaches, with only five treatment sessions. This is accomplished by delivering a higher dose per day, which requires significant precision and accuracy with expertise from the treating radiation oncologist as well as a team of medical physicists, medical dosimetrists, and radiation therapists. Modern and advanced linear accelerator technology is also required. Overall, SBRT planning and treatment delivery requires six visits to the department (one planning visit and five treatment visits).
Prostate Motion and Image Guided Radiotherapy
Because the prostate can move due to filling up and emptying of the bladder and rectum, pinpoint accuracy is required for SBRT. In order to make sure that the prostate is accurately targeted and tracked, we place 3 implanted markers (called fiducials) into the prostate. All of our treatment devices are equipped with onboard X-ray imagers or cone-beam CT technology that allows these markers to be tracked as the prostate moves. Also, prior to each treatment session, a cone-beam CT is obtained in order to make sure the anatomy is stable for treatment. This generally means having a full bladder and an empty rectum. We do provide detailed instructions on preparation for treatment to each patient.
Including all of these imaging steps, prostate cancer SBRT takes 15 only minutes per treatment session with the UCLA protocol, since state of the art RapidArc treatment delivery techniques are used. Because images are used to guide treatment, the term "IGRT" or "image-guided radiotherapy" can be used when considering the precision with which SBRT is delivered.
Radiation Planning Scans
In order to actually deliver radiation, a customized radiation planning scan must be obtained after the implanted markers are placed. This is a special high resolution CT that must be done in the department of Radiation Oncology at UCLA. It is not a diagnostic scan. This is technically called a CT simulation scan.
Because the prostate is much better visualized on an MRI than on a CT scan, we also try to obtain an MRI scan to help with treatment delineation as well. Sometimes, an MRI has already been obtained during the diagnosis of prostate cancer, and this might be sufficient. Other times, a new MRI will be recommended.
Radiation Planning Process
After the CT simulation scan (±radiation planning MRI) is performed, your radiation oncologist will work with a team of medical physicists and medical dosimetrist to design a customized radiation plan. This process generally takes five business days.
The treatment itself is delivered over the course of five treatments. These are generally delivered every other business day. Each treatment itself lasts 15 minutes (inclusive of the imaging scans discussed above). The treatment is delivered using high energy, invisible X-rays.
(1) A patient-directed webinar on prostate SBRT given by Dr. Amar Kishan:
(2) A lay-media press release on the UCLA led study, first reported in October 2018
(3) A physician-directed commentary on SBRT for prostate cancer
The prostate cancer SBRT team is located in Westwood. To schedule an appointment, please call 310-825-9775. For more information on scheduling an appointment, click here.