Brachytherapy is a form of radiotherapy where radioactive sources are inserted into the cavities of the body or into the cancers. These radioactive sources such as Iodine 125 (I125), Caesium 137, Iridium-192 or others are available as seeds, pins, wires etc and are used for insertion.
Brachytherapy is used as treatment for cancer either on its own or combined with external beam radiotherapy. External beam therapy is a type of radiotherapy that is delivered by a linear accelerator.
There are many ways in which brachytherapy treatment can be used. These are
Intracavitary- where the radioactive source is inserted into a cavity or a space such as the uterus or vagina in the treatment or uterine or cervical cancers.
Interstitial brachytherapy- where the source is inserted into the cancer and surrounding tissues such as in cancers of the mouth, tongue, lip etc.
Intraluminal- where the radioactive source is inserted into a tube-like structure such as the Oesophagus or bronchus etc.
Brachytherapy treatments can also be divided into low, medium, and high dose rate depending on the amount of radioactivity emitted by the sources that are used. Low dose rate treatments emit radiation at a slower rate and here treatment may be needed for longer. On the other hand, a high dose rate treatment lasts for a shorter duration. The medium dose rate is in between the two.
The advantage of brachytherapy is that radiotherapy is delivered to the immediate area surrounding the radioactive source, thereby limiting the amount of radiotherapy to other organs around the cancer. Brachytherapy as a treatment can be very advantageous in some cancers to be able to give high doses of radiotherapy.
Many cancers can be treated with the use of brachytherapy. The common ones are listed here.
Brachytherapy is commonly used in cervical cancer as a form of treatment in patients who have radiotherapy to treat it. Brachytherapy is usually given after completion of 5-6 weeks of external beam radiotherapy.
Usually, brachytherapy in cervical cancer is done a week to two after completion of external beam therapy. Depending on the type of radioactive source used, there may be 1-6 treatments in all. A typical brachytherapy treatment is as follows.
First, the patient is taken to the operation theatre or a brachytherapy suite where under sedation or anaesthesia, an applicator is placed in the uterus. The applicator consists of 1-3 tubes which are inserted into the vagina and uterus through the vagina. These are left in place and the patient is then taken for an x-ray or a scan. Some centres may use x-rays in this stage. Others may use a CT scan while some others may use an MRI scan. These x-rays or scans are used to plan the brachytherapy treatment. The patient will be on a bed in the suite or on a ward while the treatment is being planned. The planning part of treatment is done by the radiation oncologist and the medical physicist.
Once the treatment plan is ready, the patient is taken into the treatment room where she lies on the table. A brachytherapy machine is present in the room which contains the radioactive source. The machine is connected to the applicator that was placed in the patient. Treatment is given for a period depending on the dose that is being given and the type of machine used. Once the treatment is complete, the patient can go home and return another day for the next treatment.
In patients who have treatment with a low dose rate machine, the treatment will last many hours and the patient is usually kept on a ward while on treatment. In such a situation there will be only one treatment. In those having high dose rate treatment, short spells of treatment more times are given.
Side effects of brachytherapy for cervical cancer include increased frequency of passing urine, tiredness, loose motions. Long term side effects include narrowing of the vagina, bleeding when passing motion or urine. Vaginal dilators should be used regularly to reduce risk of vaginal narrowing.
Uterine or Endometrial cancer
This is a cancer of the uterus. Here brachytherapy is used alone or after external beam radiotherapy depending on the stage of cancer at the time of diagnosis. Most patients have surgery and removal of the uterus before the start of radiotherapy. The aim of brachytherapy treatment in uterine cancer is to give a high dose of radiotherapy to an area at the top of the vagina to reduce the risk of recurrence of cancer in that area. In this treatment, a vaginal cylinder, which is about 4-5 inches in length is inserted into the vagina after the patient lies down on a table in the brachytherapy treatment room. This cylinder is then attached to the brachytherapy machine and a radioactive source is passed into the cylinder to deliver the radiotherapy to the intended area. The cylinder is kept in place for a few minutes for each treatment. Anaesthetic is not needed for the procedure and a total of 3-5 treatments are given either once or twice a week. Potential side effects of this treatment include small risk of loose motions, long term narrowing of vagina. This can be reduced by using vaginal dilators on a regular basis for some time after completion of treatment.
Brachytherapy is used to treat breast cancer after surgery in a few centres. It is not practiced commonly. Here the treatment is given at or soon after the operation to remove the breast cancer. Usually such radiotherapy is done for early breast cancers. Tubes to insert radioactive source are placed at the time of surgery and radiotherapy is given soon after that. The radiotherapy given here will be just to the area of the tumour with a small margin around it and not to the whole breast as is the case in most patients having external beam radiotherapy.
Brachytherapy is a common form of radiotherapy used to treat prostate cancer. It is used as a sole treatment in early stage prostate cancer or as a combination with external beam radiotherapy in higher risk prostate cancer.
Treatment can be low dose rate when Iodine 125 seeds are inserted into the prostate gland or high dose rate when other isotopes are used. In low dose rate brachytherapy, these iodine seeds are permanently placed inside the prostate gland. The advantage of prostate brachytherapy, particularly for early stage prostate cancer is that the treatment is completed in one sitting as compared to 4-7.5 weeks if external beam radiotherapy is used. Overall, treatments are well tolerated, and side effects are mild and include urinary and bowel related. Not all patients are suitable for treatment and this depends on the stage of the cancer, urinary symptoms the patient has, and the size of the prostate.
Head and Neck Cancer
Brachytherapy is used as a treatment for cancers in the oral cavity such as lip, tongue, oral mucosa etc. Here the treatment is given with insertion of radioactive sources such as clips, pins which are inserted into the cancer. Alternatively, thin tubes are placed into the tumour and a high dose rate source is passed into the tubes delivering radiation. Moulds from wax or other materials are made to hold the tubes if needed.
Lung and Oesophageal Cancer
Brachytherapy can be used as an option of radiotherapy in patients with lung or oesophageal cancers mainly in patients who had previous radiotherapy and there is recurrent disease. It is not done very commonly.