Preparing for SBRT: What you need to know
New advancements in external beam radiation therapy, one of the most common treatment options for prostate cancer today, has led to the development of stereotactic body radiotherapy, or SBRT. The use of sophisticated image-guided techniques in SBRT allows for maximum dose delivery to a precise location, while minimizing the impact of radiation to surrounding healthy tissue and organs.
A popular alternative to invasive surgery, SBRT is an optimal option for those with tumors that are in close relation to vital organs. It's also beneficial for those in difficult to reach locations, such as tumors of the prostate, according to health source Radiology Info, a site produced by the Radiological Society of North America and the American College of Radiology. This method of treatment can be helpful for tumors that are prone to movement within the body. If you or a loved one are considering SBRT, here is what you should know.
Prior to any treatment, an initial consultation will take place with a radiation oncologist and care team, according to the UC Davis Department of Radiation Oncology. This visit will include a medical history review, a physical exam and an analysis of MRI, CT or other imagining scans. Your doctor will walk through the various treatment options with you and together you will decide on a customized plan. This will depend on your overall health, your preferences and the stage of your cancer. It is helpful to come prepared to this consultation with a list of any concerns or questions that you may have. If a follow-up visit is not necessary, you will schedule a start date for the radiation process.
One of the very first steps of treatment planning for SBRT is stimulation, sometimes called a "marking session," the American Cancer Society (ACS) reported. This procedure is to properly locate and mark the radiation field, or treatment port, which is exactly where the radiation will be aimed. Lying down on a table, your care team will determine the best positioning for treatment and how to keep you stabilized in that way. Headrests, body molds, casts or even tape may be used during treatment to keep you in place. This immobilization is often more restrictive than in other forms of external beam radiation, given the high dosage.
"Given the high dose of radiation, precision of SBRT stimulation is crucial."
Imaging tests will likely be used to double check tumor size and location and determine whether or not the cancer has spread. Measurements will be taken and healthy tissue in the surrounding area will be outlined. Marks with permanent markers will be made on your body at the exact radiation field. Again, given the high dose of radiation used in SBRT, the precision and accuracy of this marking is crucial, according to nonprofit organization ZERO – The End of Prostate Cancer. Additionally, fiducials, or internal, prostate markers may be used as well.
Treatment dosage planning
Once stimulation has been used to plan your treatment, the amount of radiation that will be administered is determined by your radiation oncologist and care team. This can be done through dosimetry, the use of computer systems to analyze the amount of radiation that would impact healthy surrounding organs and tissue if prescribed doses were administered, according to the ACS. The total dose of radiation used in external beam therapy is generally broken down into smaller doses called fractions.
SBRT is different than traditional radiation therapies in that the advanced technology used allows for a higher dose of radiation in a shorter period of time, according to ZERO. This means fewer fractions in fewer treatments. You will receive between one and five treatments over a one to two week period, instead of the multiple dosages given during a standard eight or nine week treatment period. This dramatically cuts down on time and costs.
Preparing for treatment
Another benefit of SBRT is that it is generally performed on an outpatient basis, according to Radiology Info. Though each treatment session itself lasts less than an hour, you should expect to spend at least half the day at the clinic. Depending on your individualized treatment, it may be necessary that someone is there to drive you home afterward. Your doctor may advise that you avoid eating or drinking after midnight before the day of your treatment and he will inform you if you should stop taking any medications that day. There should be no pain associated with the radiation therapy treatments, as the procedure is similar to having an x-ray. In most cases, you will be able to resume normal activity within one to two days.
Minimizing the side effects
Though SBRT treatment has proven quite successful in recent years and there are many benefits, it is not free of all side effects. As with any form of treatment for cancer, there are several undesirable after effects that may arise. Most concerning among prostate cancer patients opting for this method of treatment are bowel and urinary dysfunctions. Radiotherapy has the potential to irritate the rectum, bladder and urethra, according to the Prostate Cancer Foundation (PCF). This irritates the prostate and may cause the leaking or dribbling of urine, inability to control the flow of urine and the need to urinate more often. Pain, blood or a burning sensation during urination is also possible.
Radiation may also lead to radiation proctitis, a condition caused by irritation to the rectum, according to the ACS. Impacting bowel function, radiation proctitis can result in blood in the stool and rectal leakage. Similar to prostate cancer surgery, impotence may also occur following SBRT treatment and fatigue is common.
These side effects can now be significantly reduced however, thanks to the innovative and game-changing SpaceOAR Hydrogel. Acting as a spacer to temporarily push the rectum away from the prostate during treatment, SpaceOAR can effectively minimize rectal injury by moving the rectum away from the region of high dose radiation. Thus, the radiation is more concentrated on the tumor in question and surrounding cancerous cells. With the combination of the higher, stronger doses of radiation from SBRT and the state-of-the-art SpaceOAR technology, prostate cancer patients are able to undergo the most aggressive kind of treatment with the least amount of side effects. For a complete list of potential risk, warnings and precautions, as well as the procedure details, please see the SpaceOAR system instructions.