The most common type of radiation therapy is external beam radiation, which uses high-energy X-rays that are delivered from outside of the body.
Brachytherapy is different. It delivers radiation therapy with a small radioactive pellet, or source, that is about the size of a grain of rice. The source is positioned precisely inside the patient’s body, close to or inside the tumor. In some cases, the sources remain in place for just a few minutes. Other times, they are left in place for several months.
Brachytherapy allows doctors to deliver radiation directly to the patient’s tumor while limiting radiation exposure to healthy tissue.
It is a good option when the type of cancer makes the tumor easy to reach with minimally invasive techniques, such as the use of an applicator device or needle. Brachytherapy is commonly used to treat prostate cancer and gynecologic cancers including cervical cancer, endometrial cancer and vaginal cancer, among other diseases.
Types of brachytherapy
There are three primary ways doctors deliver brachytherapy:
Low-dose brachytherapy places the radioactive pellets in or near the tumor for a few weeks to several months. Patients undergo this as an outpatient procedure. After the sources are placed, patients can resume their normal activities.
Pulsed-dose brachytherapy requires a hospital stay. At the start of the stay, doctors place an applicator device in or near the tumor. A machine then sends the radioactive pellets into the applicator for roughly 10-15 minutes every hour for about two days. The procedure may be repeated after a few weeks.
High-dose brachytherapy also uses an applicator device. The radiation from the pellet is more powerful than pulsed-dose, so the patient receives just one 10-minute exposure every few days for two to three weeks. High-dose brachytherapy is an outpatient procedure.
Brachytherapy side effects
Side effects for brachytherapy are usually limited to the area near where the sources are placed. For example, cervical cancer patients who receive brachytherapy may experience bladder problems such as discomfort when urinating.
Brachytherapy for gynecologic cancers
Brachytherapy is a common treatment for many gynecologic cancers, including cervical, uterine and vaginal cancers. It is standard for cervical cancer patients to receive brachytherapy after external beam radiation. Uterine cancer patients who can’t undergo surgery also get brachytherapy, and some patients with endometrial cancer will receive brachytherapy after surgery.
For patients who haven’t had surgery, gynecologic brachytherapy starts with the patient being put under general anesthesia. A radiation oncologist precisely places an applicator inside the patient’s vagina or uterus (depending on the type of cancer), as close to the tumor as possible. Advanced imaging technologies (such as MRI, ultrasound and CT Scans) help ensure the applicator is positioned to deliver the most effective dose of radiation, as well as determine the dose itself.
The applicator is then attached to a machine that holds a small radioactive pellet. The pellet is sent into the applicator for a short amount of time, where it irradiates the tumor before being pulled back into the machine.
Depending on the patient’s specific condition, doctors will recommend one of two approaches to this treatment. Pulsed-dose rate (PDR) brachytherapy is a two-day inpatient procedure that sends the radioactive pellet into the applicator for 15 minutes every hour. PDR patients undergo this process two times about two weeks apart.
High-dose rate brachytherapy uses a pellet with more active radiation. It is sent into the applicator just one time for 10 minutes. Patients undergo this procedure as an outpatient five times over two to three weeks. Your radiation oncologist can discuss the best approach for your treatment.
Brachytherapy is also used to treat endometrial cancer following a hysterectomy in order to eliminate any cancer cells that may remain after surgery. This is a simpler procedure where a small dome is placed into the vagina while the patient is awake. A radioactive source runs into this dome to deliver high-dose brachytherapy.
Though doctors do their best to prevent radiation from impacting healthy tissue, brachytherapy for gynecologic cancers can have some short term side effects, including soreness where the applicator was placed or a small amount of bleeding. In the long term, radiation can cause diarrhea and blood in urine or stool. If these symptoms develop and don’t resolve with medications, your oncologist may refer you to a gastroenterologist or urologist to diagnose or treat the problem.
Brachytherapy for prostate cancer
Brachytherapy is a common treatment for prostate cancer. In prostate brachytherapy procedures, several radioactive “seeds” are inserted into the prostate in order to match the exact shape and size of that organ. This ensures that the entire prostate gets the right amount of radiation. The seeds then remain in the patient, providing a long-term dose of radiation.
Brachytherapy has been used as a primary treatment for low- and intermediate-risk prostate cancer for several years. To qualify for this treatment, a patient’s cancer cannot have spread significantly outside the prostate. Doctors will also perform a physical exam, imaging exams, and evaluate current urinary symptoms to determine if this is the best treatment for the patient.
In addition, recent studies show brachytherapy is effective as an end-of-treatment “boost” for patients with high-risk diseases. This boost follows external beam radiation therapy and decreases the risk of the disease progressing.
After treatment, patients may experience temporary urinary side effects. These include burning, frequent urination, urgent urination and a weak stream. They are managed with medication and typically go away a few months after treatment.