Brachytherapy is a form of radiotherapy where a radiation source is placed inside or next to the area requiring treatment. Brachytherapy is commonly used as an effective treatment for cervical, prostate, breast, and skin cancer and can also be used to treat tumours in many other body sites.
Brachytherapy can be used alone or in combination with other therapies such as surgery, External Beam Radiotherapy (EBRT) and chemotherapy.
A course of brachytherapy can be completed in less time than other radiotherapy techniques. This can help reduce the chance of surviving cancer cells dividing and growing in the intervals between each radiotherapy dose. Patients typically have to make fewer visits to the radiotherapy clinic compared with EBRT, and the treatment is often performed on an outpatient basis. This makes treatment accessible and convenient for many patients. These features of brachytherapy reflect that most patients are able to tolerate the brachytherapy procedure very well.
Brachytherapy represents an effective treatment option for many types of cancer. Treatment results have demonstrated that the cancer cure rates of brachytherapy are either comparable to surgery and EBRT, or are improved when used in combination with these techniques. In addition, brachytherapy is associated with a low risk of serious adverse side effects.
Types of Brachytheraphy
Different types of brachytherapy can be defined according to
- The placement of the radiation sources in the target treatment area
- The rate or 'intensity' of the irradiation dose delivered to the tumour,
- The duration of dose delivery
The two main types of brachytherapy treatment in terms of the placement of the radioactive source are interstitial and contact.
- In the case of interstitial brachytherapy, the sources are placed directly in the target tissue of the affected site, such as the prostate or breast.
- Contact brachytherapy involves placement of the radiation source in a space next to the target tissue. This space may be a body cavity (intracavitary brachytherapy) such as the cervix, uterus or vagina; a body lumen (intraluminal brachytherapy) such as the trachea or oesophagus; or externally (surface brachytherapy) such as the skin. A radiation source can also be placed in blood vessels (intravascular brachytherapy) for the treatment of coronary in-stent restenosis.
- Medium-dose rate (MDR) brachytherapy is characterized by a medium rate of dose delivery, ranging between 2 Gy·h−1 to 12 Gy·h−1.
- High-dose rate (HDR) brachytherapy is when the rate of dose delivery exceeds 12 Gy·h−1. The most common applications of HDR brachytherapy are in tumours of the cervix, esophagus, lungs, breasts and prostate. Most HDR treatments are performed on an outpatient basis, but this is dependent on the treatment site.
Duration of dose delivery
The placement of radiation sources in the target area can be temporary or permanent.
- Temporary brachytherapy involves placement of radiation sources for a set duration before being withdrawn. The specific treatment duration will depend on many different factors, including the required rate of dose delivery and the type, size and location of the cancer. In LDR and PDR brachytherapy, the source typically stays in place up to 24 hours before being removed, while in HDR brachytherapy this time is typically a few minutes.
- Permanent brachytherapy, also known as seed implantation, involves placing small LDR radioactive seeds or pellets in the tumour or treatment site and leaving them there permanently to gradually decay. Over a period of weeks or months, the level of radiation emitted by the sources will decline to almost zero. The inactive seeds then remain in the treatment site with no lasting effect. Permanent brachytherapy is most commonly used in the treatment of prostate cancer.