Interstitial Brachytherapy for Gynecologic Cancers

What is brachytherapy?

Brachytherapy is a form of radiation treatment where a source of radiation is put inside your body. This allows a higher dose of radiation to directly reach the area where the tumor is or was before surgery. In the case of brachytherapy for gynecological cancers, it lessens the radiation exposure to the nearby healthy tissues, like the bowel and bladder. 

In the treatment of gynecological cancers, brachytherapy may be given along with external beam radiation. There are two types of brachytherapy used for gynecologic cancers – interstitial and intracavitary. This article will focus on interstitial. 

What is interstitial brachytherapy?

Applicator with Catheters

Interstitial brachytherapy is the use of an applicator that is placed in and close to a tumor, through the vagina or the perineum. The applicator has two components: an obturator and a template. The external template is a piece of plastic that is sutured (stitched) to the outside of your body that has holes that allow the catheters to be put in and kept in a stable position. Interstitial brachytherapy is used for a few reasons:

• Intracavitary brachytherapy applicators, which are placed inside the body, do not fit correctly.
• The tumor is large.
• The tumor has an odd shape.
• The tumor involves the lower vagina.
• The tumor cannot be reached using intracavitary applicators.

Interstitial brachytherapy is a very specialized type of brachytherapy, and it is specific to each patient's needs.

How is the applicator placed?

The applicator is put into place in the operating room after you have been given general anesthesia or an epidural and sedation. A foley catheter will be placed to collect your urine. A laparoscope, ultrasound, CT, or MRI may be used to help with the placement. Once the applicator is positioned correctly, the template is sutured to your skin. Catheters, or small tubes that look like straws, will be placed through the small holes in the template and into and/or around the tumor on the inside of your body. The applicator, catheters, and foley catheter will remain in place until all your radiation treatments are complete. Imaging will be done to ensure proper placement. The procedure can be uncomfortable and could cause pain. You will be given pain medication and it is important to speak with your provider if your pain is not managed. 

You will remain on bed rest while the applicator is in place. You will be able to lift the head of your bed to a 20-degree angle. You will not be able to move in bed except for your toes and upper body. You will be given a low residue diet (low in fiber and fat), and in some cases, medications to prevent any bowel movements. You can still have visitors and you are not radioactive. 

How is the brachytherapy administered?

Geiger Counter

Treatment often happens 1-2 times per day for a few days. Your provider will talk to you about your specific schedule. When it is time for your treatment you will be taken in your bed to the treatment room. A radiation therapist will attach the brachytherapy treatment machine to the catheters in your template. A physicist is also there to take measurements and to make any adjustments needed to the catheters. This is to make sure that everything is in the right position before starting treatment. The physicist will use a tool called a Geiger counter to check the amount of radiation before treatment. The therapist and physicist will then leave the room and the therapist will turn the machine on. The physician is also outside the room monitoring the treatment.

The radioactive source that is housed in the machine moves into the catheters. Treatment lasts about 10-20 minutes, and the machine may make a clicking sound. You shouldn’t feel any pain during your treatment. Once your treatment is done the radioactive source moves from the catheters back into the machine. The physicist will use the Geiger counter to ensure that the radiation source was fully retracted into the machine. The therapist will then disconnect the catheters from the machine. 

Keep in mind that you will be by yourself in this room as the brachytherapy is being delivered. This is to protect the staff from the effects of the radiation. Make sure that you have no needs prior to the therapy starting and that you are comfortable. You will be able to talk with your care team the entire time and if you have any emergent needs, you will be able to tell them.

How is the applicator removed?

Once all your treatments are done you may be given a medication to help you relax and possibly sleep. The applicator, catheters, foley catheter, and any other equipment will be removed. You will likely have some cramping and pain. If your pain is not managed make sure to tell your provider.

What can I expect after the treatment?

You will be kept in the hospital for a few hours or overnight after your last treatment and removal of the applicator. You will be given specific directions for your care once you go home. Things to keep in mind may include:

• You may have vaginal discharge. You can use a pad but should not use tampons to manage the discharge. This can be pinkish in color and should not last for longer than a few days.
• You may have cramping, like menstrual cramps, for 24 hours after the procedure. You may use ibuprofen (Advil, Motrin or Nuprin) or naproxen (Aleve or Naprosyn) to relieve the cramps. Be sure to follow the instructions on the bottle.
• Some patients have diarrhea. You can take over-the-counter medications, such as loperamide (Imodium) or Kaopectate to help manage any diarrhea. See our managing diarrhea teaching sheet for other tips.
• You will be given vaginal dilators to use once your treatment is done. These will help the vaginal tissue remain flexible, making intercourse more pleasant, but also making pelvic exams more comfortable. You will need to use the dilator for the rest of your life. See our teaching sheet on dilators to learn more about them.
• You are not in any way radioactive after the procedure, and it is safe for friends and family to be around you.

Reasons to call your care team:

• You develop a fever.
• You have pain that is not relieved with over-the-counter medication.
• You have excessive bleeding (more than a menstrual period) or develop a vaginal discharge.
• You have burning or blood in the urine more than 24 hours after the procedure.
• You do not have a bowel movement for 3-4 days after the procedure.
• You have more than 3-4 episodes of liquid diarrhea a day. 

The process and techniques used to deliver interstitial brachytherapy are very specific to the center where you are receiving your therapy. Do not hesitate to ask questions regarding your care.