What does brachytherapy for cervical cancer involve?
There are three types of brachytherapy which can be used to treat cervical cancer:1
- Low dose rate (LDR) brachytherapy
- High dose rate (HDR) brachytherapy
- Pulsed dose rate (PDR) brachytherapy
All three types provide effective radiotherapy for cervical cancer, by placing a source of radiation directly next to the cancer. The difference between them is how often the radiation is delivered and how ‘intense’ the radiation is.
Low dose rate (LDR) brachytherapy uses sources that give out a low level of radiation. To deliver the total dose of radiation, the sources have to remain next to the cancer for an extended period of time. Therefore, treatment is usually spread out over the course of one week and requires a stay in hospital.1
In contrast, high dose rate (HDR) brachytherapy uses sources that give out a higher level of radiation. The total dose of radiation can therefore be given in shorter sessions than LDR brachytherapy.1 As such, patients can often receive treatment on an outpatient basis (i.e. you may not need an overnight stay in hospital). However, each session of treatment has to be spread out. Typically, 2-5 short sessions of treatment are required,1 each a few days to a week apart. HDR brachytherapy is more commonly used to treat cervical cancer than LDR brachytherapy as it is often more convenient for patients.
Pulsed dose rate (PDR) brachytherapy is a cross between LDR and HDR brachytherapy. It provides short pulses of radiation to the cancer using a source that gives out a high level of radiation. However these pulses are spread out (e.g. one short pulse every hour) so that it simulates LDR brachytherapy.
Treatment procedure – LDR brachytherapy
There are three main stages to the procedure: a) planning, b) treatment delivery and c) post-procedure monitoring.
The planning stage first involves having a scan, such as an:
- Ultrasound scan;
- Computerised Tomography (CT) scan;
- Computer Axial Tomography (CAT) scan;
- Magnetic Resonance Imaging (MRI) scan.
The scan provides an accurate picture of the tumor and its position. This image helps the doctor calculate how much radiation is needed to treat the cancer and where the radiation should be targeted in the cervix.
Using the plan as a guide, the doctor will place plastic applicators (and sometimes additional catheters) into the vagina and womb. To prevent the applicator +/- catheters from moving, protective gauze may be used to cushion the applicator/catheters in place. An anesthetic is normally given during the placement of the applicator and catheters to avoid any discomfort. A catheter for urine will also be placed so that patients do not have to get out of bed to go to the toilet during their treatment.
The applicator and catheters are then attached to a computer controlled machine, known as an afterloader.
The afterloader sends small radiation sources down the applicator and catheters to the treatment site in and around the cervix.
The radiation sources are then left in place for a predetermined period of time.
The computer is programmed to control very accurately where the radiation is delivered and how long it remains in the cervix. This ensures that a very precise and accurate dose of radiation is delivered to the tumor.
The precision reduces the risk of healthy surrounding tissues or organs being damaged by the radiation.
After the set period of time, the radiation sources are transferred back out of the cervix along the applicators and catheters back into the afterloader.
Will I have to stay in the hospital?
If you have LDR (or PDR) brachytherapy, it will involve staying in hospital throughout the complete course of the treatment (typically a few days).
The applicators and catheters will remain in place for the duration of the stay.
If you experience any discomfort from the applicators and catheters, painkillers can be provided.
A follow-up appointment will be scheduled approximately 4 to 6 weeks after the procedure course has finished.
This appointment is to check that the treatment is going well and monitor for any possible side effects.
Treatment procedure – HDR brachytherapy
HDR brachytherapy uses a higher intensity of radiation than LDR brachytherapy. It is more commonly used than LDR brachytherapy, as it has a much shorter treatment time, making it more convenient.
The planning for HDR brachytherapy is very similar to the planning process for LDR brachytherapy (see above).
The patient first has a scan, providing the doctor with a picture of the tumor and the cervix. This enables the doctor to plan how much radiation is needed to treat the cancerous tumor and where the radiation needs to be targeted.
Treatment delivery is also very similar to the treatment delivery for LDR brachytherapy (see above).
Applicator and catheter placement
Plastic applicators +/- catheters are placed in the vagina and womb. The applicators and catheters are connected to a computer controlled machine, known as an ‘afterloader’.
The afterloader sends radiation sources along the applicators to the treatment site. The radiation source remains in place for a short period of time. The afterloader then removes the radiation sources and then the applicators are removed.
How does this differ to LDR brachytherapy?
The main difference to LDR brachytherapy is that HDR brachytherapy uses a radiation source that emits a more intense level of radiation. Therefore, at each session of treatment, the radiation dose can be given more quickly.
You will need several (usually between 2-5) short sessions of treatment, each about a week apart. Each session can be completed in 1 day.
Will I have to stay in the hospital?
HDR brachytherapy is usually given as an outpatient treatment, meaning you probably won't need to stay in hospital overnight.
A follow-up appointment will be scheduled for approximately 4 to 6 weeks after the procedure course has finished. This appointment is to check that the treatment is going well and monitor for any possible side effects.
The short treatment time and convenience of HDR brachytherapy makes it a very practical treatment choice for many patients. Your doctor will be able to advise you if HDR brachytherapy is a possible treatment option for you.
1. Viswanathan AN, Petereit DG. In: Brachytherapy: applications and techniques. Devlin PM (Ed). Philadelphia, PA, LWW. 2007.