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All types of radiation therapy use ionizing radiation to kill cancer cells. The oldest and still the most commonly used form of radiotherapy is external beam therapy, in which an external source of radiation is targeted to a patient’s tumor. One of the principle problems with this type of radiotherapy is that it is not highly specific. Many people who receive this therapy find that healthy tissue is also damaged, leading to side effects such as pain and nausea.
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Brachytherapy is an entirely different type of radiation therapy which has some particular advantages over external beam therapy. Also called sealed source therapy, this treatment involves the placement of tiny radioactive rods, called seeds, next to or inside a tumor. The seeds emit radiation over very short distances, meaning that the radiation is very specifically targeted to cancer cells.
The main advantage of this treatment is that side effects and toxicity are greatly reduced compared to external beam radiation. Side effects are reduced because brachytherapy has the ability to target cancer cells with greater specificity. Another advantage is that the methods used to implant seeds are usually non-invasive, and are not physically demanding.
Brachytherapy is most often used to treat localized tumors in people with prostate cancer, cervical cancer, some types of mesothelioma, head or neck cancers, skin cancers, and several others.
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Brachytherapy has few specific disadvantages when compared to conventional radiotherapy. Most are side effects of the radiation itself, rather than the specific method with which it is targeted to the cancer.
For example, even though the toxic side effects of brachytherapy are lower in general than external beam radiotherapy, both treatments can sometimes cause infertility or impotence when used to treat prostate cancer.
Another risk is that there is the potential for some people being treated with brachytherapy to emit trace amounts of radiation in their urine. The level of radiation is so small that it is essentially harmless; however some precautions are required because pregnant women and small children are considered to be more sensitive to radiation. Concerns over radiation emission should be discussed with a doctor or other healthcare professional to ensure any required safety precautions are taken.
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Types of Brachytherapy
Brachytherapy seeds are tiny – around the size of a grain of rice – and are typically implanted into the body via a needle. This type of implantation is not suitable for all types of cancer; in some cases seeds are placed in a container, which is surgically implanted within or next to a tumor or within a body cavity.
Brachytherapy treatment can be either temporary or permanent.The type of treatment a patient has depends on the type of cancer involved, its location, and the size of the tumor.
In temporary treatment, the seeds are placed inside the body for a short time only, and are then removed. In general, temporary treatment is used when high-dose radiation is required to treat the cancer.
In contrast to temporary brachytherapy, in permanent treatment, the seeds are implanted and then stay in the body, rather than being removed. When seeds are implanted for permanent treatment they emit low-dose radiation for between three and twelve months. The duration of emission depends on the dosage of radiation being used, as well as the other factors described above.