Brachytherapy

Brachytherapy is commonly used as an effective treatment for cervical, prostate, breast, esophageal and skin cancer and can also be used to treat tumours in many other body sites.

[1] Treatment results have demonstrated that the cancer-cure rates of brachytherapy are either comparable to surgery and external beam radiotherapy (EBRT) or are improved when used in combination with these techniques.

Brachytherapy contrasts with unsealed source radiotherapy, in which a therapeutic radionuclide (radioisotope) is injected into the body to chemically localize to the tissue requiring destruction.

It also contrasts to External Beam Radiation Therapy (EBRT), in which high-energy x-rays (or occasionally gamma-rays from a radioisotope like cobalt-60) are directed at the tumour from outside the body.

These are enclosed in a protective capsule or wire, which allows the ionizing radiation to escape to treat and kill surrounding tissue but prevents the charge of radioisotope from moving or dissolving in body fluids.

These characteristics of brachytherapy provide advantages over EBRT – the tumour can be treated with very high doses of localised radiation whilst reducing the probability of unnecessary damage to surrounding healthy tissues.[1]: Ch.

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.

[21][31] However, a key advantage of HDR treatment is that each dose can be delivered on an outpatient basis with a short administration time[2] providing greater convenience for many patients.

Research shows locally advanced carcinoma of the cervix must be treated with a combination of external beam radiotherapy (EBRT) and intracavity brachytherapy (ICBT).

20 [33][34] Permanent seed implantation is suitable for patients with a localised tumour and good prognosis[33][35][36][37] and has been shown to be a highly effective treatment to prevent the cancer from returning.

[35][38] The survival rate is similar to that found with EBRT or surgery (radical prostatectomy), but with fewer side effects such as impotence and incontinence.

[43][45] More recently, brachytherapy alone is used to deliver APBI (accelerated partial breast irradiation), involving delivery of radiation to only the immediate region surrounding the original tumour.

[53] In a clinical study, GammaTile Therapy improved local tumor control compared to previous same-site treatments without an increased risk of side effects.

The large diameter applicators or balloon type catheter are used with the afterloader to expand the esophagus and facilitate the delivery of radiation dose to tumor with sparing of nearby normal tissue.

This is especially relevant for cancers on the nose, ears, eyelids or lips, where surgery may cause disfigurement or require extensive reconstruction.[1]: Ch.

[67] Brachytherapy can be used in the treatment of coronary in-stent restenosis, in which a catheter is placed inside blood vessels, through which sources are inserted and removed.

[68] In treating In-stent restenosis (ISR) Drug Eluting stents (DES) have been found to be superior to Intracoronary Brachytherapy (ICBT).

Acute side effects associated with brachytherapy include localised bruising, swelling, bleeding, discharge or discomfort within the implanted region.

[75] Most of the acute side effects associated with brachytherapy can be treated with medication or through dietary changes, and usually disappear over time (typically a matter of weeks), once the treatment is completed.

[72] In a small number of people, brachytherapy may cause long-term side effects due to damage or disruption of adjacent tissues or organs.

As a precaution, some people receiving permanent brachytherapy may be advised not to hold any small children or be too close to pregnant women for a short time after treatment.

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.[1]: Ch.

Temporary brachytherapy involves placement of radiation sources for a set duration (usually a number of minutes or hours) before being withdrawn.[1]: Ch.

1  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.

These include x-ray radiography, ultrasound, computed axial tomography (CT or CAT) scans, and magnetic resonance imaging (MRI).[1]: Ch.

Imaging techniques, such as x-ray, fluoroscopy and ultrasound are typically used to help guide the placement of the applicators to their correct positions and to further refine the treatment plan.[1]: Ch.

This serves as a guide for the brachytherapy team to refine the distribution of the sources and provide a treatment plan that is optimally tailored to the anatomy of each patient before actual delivery of the irradiation begins.

[84] In contrast, afterloading involves the accurate positioning of non-radioactive applicators in the treatment site, which are subsequently loaded with the radiation sources.

[89] In the early twentieth century, techniques for the application of brachytherapy were pioneered at the Curie institute in Paris by Danlos and at St Luke's and Memorial Hospital in New York by Robert Abbe.[1]: Ch.

1 Following initial interest in brachytherapy in Europe and the US, its use declined in the middle of the twentieth century due to the problem of radiation exposure to operators from the manual application of the radioactive sources.

Body sites in which brachytherapy can be used to treat cancer
Dose calculation geometry
Typical stages of a brachytherapy procedure
Creation of a virtual patient to plan the delivery of brachytherapy
Refinement of the treatment plan during a brachytherapy procedure