Brachytherapy dates back to 1901 (shortly after the discovery of radioactivity by Becquerel in 1896) when Pierre Curie suggested to Henri-Alexandre Danlos that a radioactive source could be inserted into a tumour.
It was found that the radiation caused the tumour to shrink.
However, the development of remote afterloading systems and the use of new radioactive sources in the 1950s and 1960s, reduced the risk of unnecessary radiation exposure to the operator and patients. LDR brachytherapy is commonly used for cancers of the oral cavity, oropharynx, and prostate cancer
- Medium-dose rate (MDR) brachytherapy is characterized by a medium rate of dose delivery, ranging between 2 Gy.hr-1 to 12 Gy.hr-1. lungs, breasts
- Pulsed-dose rate (PDR) brachytherapy involves short pulses of radiation, typically once an hour, to simulate the overall rate and effectiveness of LDR treatment. Typical tumour sites treated by PDR brachytherapy are gynaecological
- Permanent brachytherapy, also known as seed implantation, involves placing small LDR radioactive seeds or pellets (about the size of a grain of rice) 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. eye, head and neck region (lip, floor of mouth, tongue, nasopharynx and oropharynx), urinary tract (bladder, urethra, penis), female reproductive tract (uterus, vagina, vulva), and soft tissues.
Patients receiving brachytherapy generally have to make fewer visits for radiotherapy compared with EBRT, and overall radiotherapy treatment plans can be completed in less time.
Many brachytherapy procedures are performed on an outpatient basis. This convenience may be particularly relevant for patients who have to work, older patients, or patients who live some distance from treatment centres, to ensure that they have access to radiotherapy treatment and adhere to treatment plans. Shorter treatment times and outpatient procedures can also help improve the efficiency of radiotherapy clinics.
Brachytherapy can be used with the aim of curing the cancer in cases of small or locally advanced tumours, provided the cancer has not metastasized (spread to other parts of the body). In appropriately selected cases, brachytherapy for primary tumours often represents a comparable approach to surgery, achieving the same probability of cure and with similar side effects.
However, in locally advanced tumours, surgery may not routinely provide the best chance of cure and is often not technically feasible to perform. In these cases radiotherapy, including brachytherapy, offers the only chance of cure.
In more advanced disease stages, brachytherapy can be used as palliative treatment for symptom relief from pain and bleeding.
In cases where the tumour is not easily accessible or is too large to ensure an optimal distribution of irradiation to the treatment area, brachytherapy can be combined with other treatments, such as EBRT and/or surgery. Combination therapy of brachytherapy exclusively with chemotherapy is rare.
Cervical cancer
Brachytherapy is commonly used in the treatment of early or locally confined cervical cancer and is a standard of care in many countries. Cervical cancer can be treated with either LDR, PDR or HDR brachytherapy. Used in combination with EBRT, brachytherapy can provide better outcomes than EBRT alone.
The precision of brachytherapy enables a high dose of targeted radiation to be delivered to the cervix, while minimising radiation exposure to adjacent tissues and organs.
The chances of staying free of disease (disease-free survival) and of staying alive (overall survival) are similar for LDR, PDR and HDR treatments. However, a key advantage of HDR treatment is that each dose can be delivered on an outpatient basis with a short administration time.
Permanent seed implantation is suitable for patients with a localised tumour and good prognosis and has been shown to be a highly effective treatment to prevent the cancer from returning. Permanent seed implantation is often a less invasive treatment option compared to the surgical removal of the prostate.
HDR brachytherapy as a boost for prostate cancer also means that the EBRT course can be shorter than when EBRT is used alone.
Breast cancer
Radiation therapy is standard of care for women who have undergone lumpectomy or mastectomy surgery, and is an integral component of breast-conserving therapy.
Brachytherapy can be used after surgery, before chemotherapy or palliatively in the case of advanced disease. Brachytherapy to treat breast cancer is usually performed with HDR temporary brachytherapy. Post surgery, breast brachytherapy can be used as a “boost” following irradiation of the whole breast using EBRT.
More recently, brachytherapy alone is applied in a technique called APBI (accelerated partial breast irradiation), involving delivery of radiation to only the immediate region surrounding the original tumour.
With breast brachytherapy, radiation oncologists place a flexible plastic tubes called catheters or a balloon into the breast. Twice a day for a determined number of days, the catheters or the balloon will be connected to a brachytherapy machine, also called a high-dose-rate afterloader to safely and effectively deliver the radiation to the lumpectomy site under computer guidance. The radiation is only left in place for a few minutes at a time. At the end of the course of treatment, the catheter or balloon is removed. This treatment is still being studied to see if it is as effective as three to eight weeks of external beam radiation therapy.
Skin cancer
HDR brachytherapy for nonmelanomatous skin cancer, such as basal cell carcinoma and squamous cell carcinoma, provides an alternative treatment option to surgery. This is especially relevant for cancers on the nose, ears, eyelids or lips, where surgery may cause disfigurement or require extensive reconstruction. Treatment times are typically short, providing convenience for patients.
It has been suggested that brachytherapy may become a standard of treatment for skin cancer in the near future.
The therapy has also been investigated for use in the treatment of peripheral vasculature stenosis and considered for the treatment of atrial fibrillation.
Further Reading
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