Radiation therapy typically is delivered as high-energy beams that are aimed directly at a patient’s tumor. This is known as external beam radiation.
Brachytherapy is different. It delivers radiation therapy with small pieces of radioactive material (usually about the size of a grain of rice) that are placed inside the patient’s body as close to the tumor as possible. This allows doctors to deliver very high doses of radiation directly to the patient’s tumor while limiting radiation exposure to healthy tissue.
Brachytherapy is used to treat several different diseases, including breast cancer, gynecologic cancers and prostate cancer.
Accelerated partial breast irradiation, or APBI, uses radioactive seeds to kill breast cancer cells that may remain after lumpectomy surgery. APBI delivers a powerful dose of radiation while greatly reducing treatment time.
APBI is performed about one to four weeks after a lumpectomy. A specialized catheter is inserted into the cavity left behind after the tumor is removed. The device remains in place during the course of APBI treatment, usually about five to seven days.
During treatment, the seed, about the size of a grain of rice, is inserted into the catheter. It stays within the device in various positions for five to 10 minutes. It is withdrawn and then re-inserted six hours later, for a total of two treatments per day.
APBI is best for women who are over 50 years old. Their tumors should
- have clear margins
- measure three centimeters or less
- show no sign of the disease spreading to nearby lymph nodes
When compared with standard radiation treatment, APBI offers significant benefits. At less than a week, the treatment is far shorter than external beam radiation, which usually lasts four to six weeks. In addition, the radiation dose is concentrated on tissue surrounding the lumpectomy cavity. This spares normal tissue and critical organs such as the heart and lungs from unnecessary radiation.
Women with early stage breast
cancer have so many different treatment
options that the choices can be overwhelming. For almost all women
who choose to keep their breast (and avoid mastectomy), radiation
therapy is almost always a part of the treatment plan.
The radiation regimen for which we have the longest follow-up data involves treating the whole breast, every day for five weeks, typically with an additional one-week "boost" to the area where the tumor used to be.
For women who want the most conservative modality of radiation treatment, I recommend this longer course of treatment.
The question has become, as technology has improved, can we be more focal and efficient in how we deliver radiation therapy. Accelerated partial breast irradiation (APBI) lets me deliver relatively higher doses of radiation to the area where the tumor used to be, twice a day for five days.
This technique is still actively being compared to the traditional longer course of whole breast radiation. What we do have is follow-up data from multiple institutions in the United States and Europe that have shown very high rates of tumor control in appropriately selected patients, with 5-12 years of follow-up.
I use very strict criteria before offering APBI to patients and encourage all of my patients to be treated on protocol. The patients I treat with APBI have very early stage, small breast cancer that has been completely removed by their surgeon. I also evaluate each of my patients with a CT scan after surgery.
This lets me measure the exact dimensions of the area removed by the
breast surgeon and to calculate if the patient can be suitably treated
by one of the modalities we have available to deliver APBI.
How to receive APBI
At MD Anderson, we offer two main ways to deliver APBI to patients, one that's internal and one that's external.
Brachytherapy is a way to deliver very focused radiation inside the body in exactly the area where the tumor used to be. This technique takes advantage of the joint expertise of the breast surgeon and the radiation oncologist, and I enjoy being able to collaborate closely with my colleagues in breast surgery on these cases.
The surgeon places a catheter into the breast using local anesthesia in an outpatient setting. I then work with a medical physicist to design a treatment that is uniquely tailored to the anatomy of the patient. I'm present at each treatment my patients receive using a high-dose radioactive source that sits temporarily in the catheters.
Some patients tell me they prefer to not have a catheter placed inside the breast, in which case I offer APBI using external techniques including either protons or photons. These techniques use more than one beam of radiation to deliver focused treatment to the area surrounding where the tumor used to be.
My patients with early stage breast cancer have a lot of treatment options. I hope that in the conversations we have together that my patients can choose the treatment that fits them best.
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 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.