Brachytherapy

DEFINITION: Brachytherapy is a form of radiation treatment in which the radioactive source consists of small pellets, seeds, ribbons, or wires, each about the size of a grain of rice, that are placed into or next to the area being treated. Brachytherapy is derived from a Greek word meaning “short” and literally means “short-distance treatment.” It is unlike radiation from an external source, such as a machine, in which the radioactive beam is directed at the tumor from outside the body.

ALSO KNOWN AS: Sealed source radiotherapy, endocurietherapy

There are three types of brachytherapy delivery. Intracavity treatment involves radioactive implants that are placed inside a body cavity, such as the uterus. In interstitial treatment, radiation implants are placed directly in the tumor. They are often permanent and commonly used in prostate cancer treatment. In unsealed internal radiation therapy, radioactive materials are injected into a vein or body cavity.

Brachytherapy can be either permanent or temporary. Permanent brachytherapy, or low-dose rate (LDR) brachytherapy, is often called seed implantation and involves placing small, radioactive seeds at or near the tumor and leaving them there permanently. This is typically used in the treatment of prostate cancer. The radioactivity of the seeds decreases over time, and the seeds left inside the patient cause no discomfort or harm. Temporary brachytherapy, or high-dose rate (HDR) brachytherapy, involves radioactive seeds that are left in the body only for a specific amount of time and then are removed. Treatments may involve several visits to the physician to have the seeds placed and removed. This method is used in the treatment of most other cancers.

Radiation works by killing cancer cells when they are trying to multiply. The deoxyribonucleic acid (DNA) of cancer cells is more sensitive to radiation than that of normal cells, so ideally the cancer cells die, and the normal cells are able to repair themselves.

Cancers treated: Brachytherapy is used for many types of cancer in the body, including prostate, cervical, head and neck, ovarian, breast, lung, gallbladder, uterine, and vaginal cancers, as well as anal/rectal tumors and sarcomas. It can also be used to treat noncancerous conditions such as benign tumors and coronary artery disease. Additionally, brachytherapy can be used in conjunction with other cancer treatments, including chemotherapy and external-beam radiation. It can be used as both a curative and a palliative form of treatment.

Why performed: Brachytherapy has been in use since the early twentieth century, and it has been proven to be safe and effective. It allows a higher dose of radioactivity to be used with decreased risk of damage to healthy tissue, quicker healing times, and decreased risk of infection. In breast brachytherapy, for example, the therapy is quicker than external beam radiation, and it only treats a portion of the breast. Brachytherapy often can be performed in five days as opposed to five to seven weeks. The patient has a better cosmetic result, and healthy tissue is preserved.

Patient preparation: Before the treatment begins, patients meet with the physician and receive instructions on how to care for themselves after the treatment. The physician will determine what tests should be done prior to brachytherapy, which may include blood tests, electrocardiograms (ECG or EKG), and x-rays. The actual prepping of the patient depends on where the seeds are being placed. Typically, a radiation oncologist, a radiation physicist, a dosimetrist, and a radiation therapist are involved in planning the treatment. The radiation oncologist determines the type of treatment needed and is responsible for the overall treatment plan, including the area to be treated and the dose to be delivered. The physicist calculates the dose to be prescribed. The dosimetrist assists in dose calculation and helps in delivering the prescribed dose. The radiation therapist operates the equipment and delivers the dose. Through special computer programs, the dose, duration, and delivery method of the treatment are determined. Without this specific calculation, the cancer cells might receive too little radiation and the normal tissue could receive too much.

Steps of the procedure: The steps of the procedure also vary depending on where the seeds are being placed in the body. The seeds are generally inserted into the site of the tumor through a needle or catheter. Sometimes a device to hold the seeds is placed near the tumor. Often, X-rays, ultrasound, computed tomography (CT) scans, or even surgery is used to help position and verify placement of the radioactive material or device.

Some doses are delivered to the patient on an outpatient basis, with the radiation delivered to the tumor in a short amount of time, after which the delivery device is removed and the patient goes home. The patient may return at intervals for more treatment. Alternatively, a patient may spend a couple of nights in the hospital so that the delivery device can remain in place and the radioactivity can be delivered at a continuous rate. These patients are placed in private rooms, usually with limited or no visitors allowed. The hospital staff will continue to take care of the patient, but they limit the amount of time that they spend with the patient in order to keep their radiation exposure low.

A patient may have an intravenous line inserted in order to receive medications. Sedatives or anesthesia may also be used to place the delivery device, again depending on the location of the treatment.

After the procedure: Patients typically can go home after the LDR procedure. The physician will give the patient detailed instructions for self-care at home, which may include limiting contact with pregnant women or children for a limited amount of time so as not to expose them to the radioactivity. The patient may have some pain, swelling, or bleeding at the site of the procedure. Educational materials may be very helpful to the patient and family after the procedure. Side effects and precautions can be outlined. Generally, the patient is to avoid heavy lifting or strenuous physical activity for a few days after the procedure. Sometimes the radiation precautions include instructing the patient to sleep alone for a period of time, to avoid sexual relations for a period of time, and to use tweezers, not bare hands, to pick up any seed that may become dislodged. Instructions on what to do with a dislodged seed are also given.

HDR patients are usually in the hospital for forty-eight to seventy-two hours and then are discharged once the radiation device is removed. They also receive detailed instructions on how to protect family members from exposure and to watch for side effects such as pain and bleeding.

Risks: Like the preparation of the patient and the steps of the procedure, the risks from brachytherapy also vary depending on the area treated. Although relatively safe, brachytherapy is not totally without risks. Patients with permanent brachytherapy seeds continue to give off small amounts of radiation for several weeks. With this type of treatment, there is a risk that the seeds will move out of place. Patients are often told to strain their urine at home in case in seeds do migrate. Patients are given special instructions from their doctor about protecting family members from exposure.

Brachytherapy for prostate cancer can cause sexual dysfunction such as impotence and bowel problems such as diarrhea, although these are not very common. Urinary irritation is a more common side effect because the urine stream becomes obstructed by swelling in the prostate after therapy. A urinary or Foley catheter is placed to allow urine to flow. The prostate usually returns to normal size and the blockage disappears after several weeks, and the catheter can then be removed. Patients may continue to have some urinary burning for a few weeks, but this also resolves.

Some minor, low-risk side effects include bruising, swelling, pain, or discomfort at the site of implantation.

Recurrence and further malignancy is also a risk. A study published in 2024 in The Journal of Urology found a link between brachytherapy and secondary malignancy. According to the study, around six percent of brachytherapy-treated men had secondary malignancies, particularly in the pelvic region, at fifteen-year follow-ups, and that likelihood increased to almost 10 percent after twenty years. By contrast, a little over three percent and a little over four percent of surgically-treated men developed secondary pelvic malignancies over the same durations. However, there was no difference in deaths from secondary malignancies between the two groups.

Results: The physician may order scans or X-rays after brachytherapy in order to determine if the treatment was successful. The effectiveness of brachytherapy varies depending on the location of the treatment and the type of cancer. It has proven to be effective in many types of cancer, especially cervical cancer and prostate cancer. In early prostate cancer, brachytherapy offers ten-year survival rates comparable to surgical removal of the prostate, according to several studies. In general, patients have fewer side effects and a quicker recovery time with this therapy as compared to external beam radiation or surgery. There is also less risk of infection than with surgery. As a result, patients typically have a better with this procedure, which is easier to tolerate.

Bibliography

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