Brachytherapy is an essential component of treatment in the management of gynecologic cancers. Recent studies demonstrate that women actually live longer when they receive brachytherapy (definitive cervical cancer, medically inoperable endometrial cancer, vaginal cancer) than if brachytherapy is replaced with just external beam radiation therapy.
Not all centers have the expertise to perform brachytherapy and those that do aren’t always able to offer all types of brachytherapy (interstitial and intracavitary). There are also important advances in brachytherapy including the movement away from 2-dimmensional planning to 3-dimmensional planning with either CT or MRI. This is a major advance in gynecologic brachytherapy that is improving local control outcomes and reducing the risk of short and late term side effects.
It is important to be evaluated and treated at a center that has experience and expertise in offering the full range of possible treatments so that the most appropriate one is selected and performed safely.
Overview of contents
Intracavitary brachytherapy refers to when an applicator is placed directly into a “cavity”. In gynecologic cancers this refers to placing an applicator in the vagina either up to the vaginal apex in cases where the cervix and uterus have been removed such as in endometrial cancer or through the cervical os and into the uterus for women being treated for cervical cancer.
Below is a cartoon to help better illustrate an intracavitary applicator that might be used to treat the vaginal cuff. You can see the bladder in yellow, the vagina in the blue cylinder, the brachytherapy applicator in the light blue rectangle with the radiation dwell positions in red, and the rectum in brown. With a single channel applicator the radiation dose spreads out from the central part of the applicator essentially in circles. The most intense dose of radiation is nearest the radiation source and the radiation dose gets less intense the farther away from the source you go.
Below is an actual example of a vaginal cylinder applicator (a 13 channel applicator) and the distribution of radiation dose that was delivered around the vaginal apex (left image). A 3D depiction of the anatomy and distribution of the radiation dose (bladder in yellow, rectum in brown, applicator in purple, radiation dose in red) (right image)
Intracavitary applicators are also used to treat cervical cancer and the most commonly used applicator is a tandem and ovoid applicator that can be seen below.
Intracavitary brachytherapy is commonly used in the post-operative treatment of endometrial cancer. The treatment is most commonly given either as 3 separate outpatient treatments usually 2 times per week or as 6 separate outpatient treatments given every other day. For the first treatment the patient lays down on her back on a CT scanner table. A vaginal cylinder is gently placed in the vagina by a physician and stabilized with a base plate. A CT scan is done of the pelvis to confirm that the cylinder is truly at the top of the vagina. Once this is confirmed then the end of the cylinder is connected via a transfer tube to the HDR afterloader. The HDR afterloader has a motorized cable with a small radiation source welded to the end of it. This radiation source is pushed to the top of the cylinder and delivers a radiation treatment over about 5-10 minutes. The source is then retracted back into the afterloader, the vaginal cylinder is removed and then the patient goes home. When the patient comes back for her subsequent treatments a repeat CT scan does not need to be performed and she will just proceed with having the applicator placed and then receiving the radiation treatment.
Brachytherapy treatment is a standard component of treatment for cervical cancer definitively treated with radiation. At our institution brachytherapy is most commonly given after completing external beam radiation therapy. It is most standardly given two times per week as an outpatient for a total of 5 treatments. Patients are given moderate sedation for the tandem and ovoid applicator placement. After the applicator is placed a CT scan or MRI is done to visualize the applicator relative to the patient’s anatomy and residual tumor. Then a customized plan is generated. Once this is ready the tandem and ovoid applicator is connected via transfer tubes to the HDR afterloader. The HDR afterloader has a motorized cable with a small radiation source welded to the end of it. This radiation source is pushed to the top of the cylinder and delivers a radiation treatment over about 5-10 minutes. The source is then retracted back into the afterloader. The applicator is then removed and the patient goes home. The whole process typically takes 2-3 hours.
Interstitial refers to brachytherapy treatment where there isn’t a cavity for a radiation applicator to fit into and so a series of small hollow little tubes are placed in and near the target tissue. An example of when this might be used is shown in the following illustrations. In the picture on the left there is an oval uterus narrowing down to the rectangular cervix that has a red cervical cancer and a larger rectangular vagina. Ideally after an initial course of external beam radiation therapy and concurrent chemotherapy this red cervical tumor will shrink and allow for a tandem and ovoid applicator (green figures) to fit into the vaginal fornices and cervix so the appropriate distribution of dose (orange) can be achieved (middle image). Sometimes a lesion does not regress at the end of external beam radiation and then may not allow the tandem and ovoid applicator to properly fit as in the picture on the far right.
In other cases the tandem and ovoid applicator would fit but the residual lesion is larger than the standard distribution of dose that could be encompassed with this applicator and so some of the tumor would be underdosed. This is illustrated in the cartoons below where the orange distribution of radiation dose dose not cover all of the red tumor. By using the green hollow tubes one can then move the radiation distribution out laterally in order to cover the entire red tumor.
An axial CT slice showing the distribution of small hollow brachytherapy tubes and the distribution of radiation dose for an actual gynecologic interstitial brachytherapy implant.
These are cases that are performed in an operating room. The patient is given an epidural. Typically this will be combined with sedation for the case however some patients may undergo general anesthesia. In the operating room while you are asleep the small hollow tubes will be placed to cover the tumor. At the end of the case the hollow tubes will be stabilized through a plastic template that will be sutured to the skin. When you wake up you won’t be able to get up out of bed and walk around as the template would be displaced. So you need to remain in bed either on your back or on your side until all of the treatment is completed. After spending time in recovery you will be brought to the Radiation Oncology Department and a CT scan will be performed to verify the correct position of all of the tubes that were placed in the operating room. Then we will work on a customized plan. Once the plan is approved you will be treated up to two times per day until completing treatment. You will remain in the hospital the whole time that you are receiving this treatment.
One of the most important advances in gynecologic brachytherapy is the movement from 2-dimmensional to 3-dimmensional planning. This allows us to improve the radiation dose coverage to the tumor while limiting excessive dose to normal tissues. There are multiple studies now demonstrating improved outcomes, for example, for cervical cancer patients treated with image guided brachytherapy compared with older 2-dimmensional techniques. An example of a tandem and ovoid applicator using 2-dimmensional planning with an X-ray on the top and example of a tandem and ovoid applicator on the bottom using CT 3-dimmensional planning.
One can immediately appreciate how much additional detail in the anatomy and distribution of the radiation dose can be appreciated on the CT scan versus the X-ray.
Moving from standardized to personalized boxes and pears in radiation planning for cervical cancer.
Mesko S, Kamrava M.
Curr Opin Obstet Gynecol. 2016
Early clinical outcomes of ultrasound-guided CT-planned high-dose-rate interstitial brachytherapy for primary locally advanced cervical cancer.
Mesko S, Swamy U, Park SJ, Borja L, Wang J, Demanes DJ, Kamrava M.
The ideal adjuvant treatment in node positive vulvar cancer is (fill in your best guess here).
Gynecol Oncol. 2015
Ureteral stent insertion for gynecologic interstitial high-dose-rate brachytherapy.
Demanes DJ, Banerjee R, Cahan BL, Lee SP, Park SJ, Fallon JM, Reyes P, Van TQ, Steinberg ML, Kamrava M.
Potential role of ultrasound imaging in interstitial image based cervical cancer brachytherapy.
J Contemp Brachytherapy. 2014
Brachytherapy in the treatment of cervical cancer: a review.
Banerjee R, Kamrava M.
Int J Womens Health. 2014
Dosimetric comparison of 3-dimensional planning techniques using an intravaginal multichannel balloon applicator for high-dose-rate gynecologic brachytherapy.
Park SJ, Chung M, Demanes DJ, Banerjee R, Steinberg M, Kamrava M.
Int J Radiat Oncol Biol Phys. 2013
Electronic brachytherapy for postsurgical adjuvant vaginal cuff irradiation therapy in endometrial and cervical cancer: a retrospective study.
Kamrava M, Chung MP, Demarco J, Kayode O, Park SJ, Borja L, Chow L, Lee SP, Steinberg ML, Demanes DJ.
American Brachytherapy Society consensus guidelines for interstitial brachytherapy for vaginal cancer.
Beriwal S, Demanes DJ, Erickson B, Jones E, De Los Santos JF, Cormack RA, Yashar C, Rownd JJ, Viswanathan AN; American Brachytherapy Society.
American Brachytherapy Society consensus guidelines for adjuvant vaginal cuff brachytherapy after hysterectomy.
Small W Jr, Beriwal S, Demanes DJ, Dusenbery KE, Eifel P, Erickson B, Jones E, Rownd JJ, De Los Santos JF, Viswanathan AN, Gaffney D; American Brachytherapy Society.
American Brachytherapy Society consensus guidelines for locally advanced carcinoma of the cervix. Part II: high-dose-rate brachytherapy.
Viswanathan AN, Beriwal S, De Los Santos JF, Demanes DJ, Gaffney D, Hansen J, Jones E, Kirisits C, Thomadsen B, Erickson B; American Brachytherapy Society.
High dose rate transperineal interstitial brachytherapy for cervical cancer: high pelvic control and low complication rates.
Demanes DJ, Rodriguez RR, Bendre DD, Ewing TL.
Int J Radiat Oncol Biol Phys. 1999
The use and advantages of a multichannel vaginal cylinder in high-dose-rate brachytherapy.
Demanes DJ, Rege S, Rodriquez RR, Schutz KL, Altieri GA, Wong T.
Int J Radiat Oncol Biol Phys. 1999
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