Brachytherapy for Early-Stage Breast Cancer

A type of radiation therapy that treats cancer at its source

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Brachytherapy, also referred to as internal radiation therapy, is a form of cancer treatment in which a sealed radioactive source is placed in or near a tumor to kill it. It is used to treat many different types of cancer, but is specifically used in breast cancer to clear cancer cells following a lumpectomy. Brachytherapy may also be used to reduce the size of a tumor prior to breast cancer surgery or as palliative treatment to reduce pain or bleeding in advanced or inoperable disease.

Breast brachytherapy is used to treat early-stage cancers that have not spread (metastasized) to other parts of the body. The treatment can be delivered in different ways and is often combined with conventional external beam radiation therapy (EBRT).

Despite strict selection criteria, an estimated 71,000 American women would benefit breast brachytherapy each year, according to a 2017 review of studies in the Journal of Contemporary Brachytherapy.

Purpose of Treatment

EBRT is the standard of care for women who have undergone a lumpectomy or mastectomy. Breast brachytherapy can help support EBRT by "boosting" the response rate and improving outcomes. In recent years, high-dose brachytherapy has been used as a standalone treatment of early-stage cancer, a procedure referred to as accelerated partial breast irradiation (ABPI).

Brachytherapy is also sometimes used in neoadjuvant therapy, a form of treatment designed to shrink a tumor before surgery. Doing so can reduce the risk of cancer recurrence by decreasing the tumor margins (the transitional areas between normal and cancerous tissue), where cancer cells hide.

One of the main advantages of breast brachytherapy compared to whole-breast irradiation is that a higher dose of radiation can be precisely delivered with less damage to surrounding tissues of the breast, ribs, and lungs.

Brachytherapy Types

Both the implants and implantation methods used in brachytherapy can vary by the cancer stage and type. The implants may be temporary or permanent and vary in size and radioactive strength. Depending on the procedure, the specialist (known as a radiation oncologist) may use radioactive seeds, pellets, capsules, ribbons, tubes, or balloons.

There are five methods used to deliver breast brachytherapy, each of which has specific purposes and indications:

  • Interstitial breast brachytherapy involves the placement of several flexible tubes (catheters) in the breast tissue through which a radiation source is placed.
  • Intracavity breast brachytherapy, also known as balloon brachytherapy, is used after a lumpectomy to deliver radiation to the breast cavity via an inflatable balloon.
  • Intraoperative radiation therapy delivers localized radiation during the lumpectomy via a cone-shaped applicator and a radiation emitter.
  • Permanent breast seed implant (PBSI) involves the permanent implantation of low-dose radioactive seeds to prevent cancer recurrence in women with early-stage breast cancer.
  • Non-invasive breast brachytherapy (NIBB) is a newer procedure that doesn't require catheters or implantation but instead delivers a concentrated beam of radiation while the breast is compressed during a mammogram.

According to a 2017 review of studies, breast brachytherapy can reduce the rate of cancer recurrence from 13.3 percent to 6.3 percent when used with EBRT.

Dosage

The type of radioactive material used in brachytherapy (typically iodine, palladium, cesium, or iridium) varies by the treatment type. The material, called the source, is encapsulated in a metal shell that controls how much radiation is emitted.

The length of time an implant is left in place depends on the type of brachytherapy used. This is directed by the dose rate, described in units called Grays per hour (Gy/hr). With breast cancer, there are five possible dose rates:

  • Ultra-low-dose rate (ULDR) brachytherapy involves seeds or pellets that emit radiation at 0.1 to 0.3 Gy/hr.
  • Low-dose rate (LDR) brachytherapy involves implants that emit radiation at 2 Gy/hr.
  • Medium-dose rate (MDR) brachytherapy emits radiation at 2 to 12 Gy/hr.
  • High-dose rate (HDR) brachytherapy emits radiation at greater than 12 Gy/hr.
  • Pulse-dose rate (PDR) brachytherapy involves short pulses of high-dose radiation, typically once per hour, to enhance the effectiveness of LDR.

Higher dose rates confer to shorter treatment times, and vice versa. With HDR brachytherapy, the implants are placed for only a few minutes at a time and then removed, with additional treatments given every several days or weeks. With LDR brachytherapy, the radioactive source may be left in for one or several days.

Of all the dose rate options, HDR brachytherapy is the one most commonly used for breast cancer. When used on its own, HDR brachytherapy can reduce the treatment time from six to seven weeks for EBRT to just five days.

LDR and MDR brachytherapy are typically used to "boost" EBRT following surgery, while ULDR brachytherapy is reserved for permanent implants, including PBSI.

PDR brachytherapy is a more recent innovation that combines the efficacy of HDR technology with the improved tissue safety of LDR brachytherapy.

Procedure

Brachytherapy requires a treatment team, which may include a radiation oncologist, dosimetristradiation therapist, nurse, and occasionally a surgeon. 

With the exception of NIBB, breast brachytherapy will involve some sort of invasive procedure. The radioactive source may be delivered using a needle-like applicator, via one or more temporary catheters, or during breast surgery.

The implantation is usually performed in a hospital operating room specially designed to keep radiation from seeping out. Depending on the procedure, you will either be given local anesthesia to numb the general area or general anesthesia to put you to sleep.

As with any procedure involving anesthesia, you will be given specific instructions as to when you may need to stop eating or drinking prior to the procedure.

Throughout the Procedure

Breast brachytherapy requires an imaging tool, such as an X-ray, ultrasound, or computed tomography (CT), to direct the placement of the radioactive source. Once the coordinates are determined, one or more sources are strategically placed to target the cancer but spare the surrounding cells.

The various procedures can be broadly described as follows:

  • With interstitial brachytherapy, several catheters are placed so that radioactive pellets can be readily inserted and removed. This is most often done one to two weeks after surgery. HDR brachytherapy is delivered in a series of 10- to 20-minute sessions. LDR brachytherapy is delivered continuously over one to two days.
  • With intracavity brachytherapy, a single catheter with an inflatable balloon is inserted into the breast cavity following a lumpectomy. Tiny radioactive pellets are then fed into the balloon. Sometimes the catheter is placed during surgery and filled with pellets in the oncologist's office several days later.
  • With intraoperative brachytherapy, the radiation is delivered into the breast cavity via a targeted emitter immediately following the lumpectomy. The treatment is usually completed in less than an hour.
  • With PBSI, the radioactive seeds are individually placed with a percutaneous applicator that inserts the seeds directly through the skin.

Following the Procedure

Following the completion of the brachytherapy procedure, you are led to the recovery room and monitored from anywhere from 30 minutes to several hours. You will likely feel localized pain around the implantation site, as well as swelling, redness, and bruising. Side effects from the anesthesia may include sleepiness, confusion, and nausea.

Some radioactive implants may be left in place from one to several days. If so, you will probably need to remain in the hospital during treatment, often in a special radiation-proof room. Larger implants may require you to stay in bed without moving.

If you have been given permanent brachytherapy seeds, you can usually go home the same day. The radiation will wear off in a couple of weeks, and the seeds will gradually deteriorate over time.

After the Procedure

If multiple treatments are required, you will need to care for the breast catheters until the treatment is completed. You will still be able to perform most daily routines and drive yourself to and from the doctor's office, but would need to take several precautions to prevent injury or infection. Among them:

  • Always wear a bra to keep the catheters securely in place.
  • Do not shower. Instead, take a sponge bath and wash your hair over the sink.
  • Avoid getting the treated breast wet.
  • Clean the catheter site daily with a solution comprised of equal parts water and hydrogen peroxide. Apply a thin layer of antibiotic cream afterward.
  • Do not pull off any Steri-Strip tapes that cover incisions on the breast or armpit. Let them fall off on their own.

Call your doctor immediately if you experience high fever (over 100.5 degrees F) or develop severe pain, redness, swelling, or pus-like discharge around a catheter or incision site.

Once you have finished treatment, the catheters will be removed and you will begin to heal. Additional evaluations to assess the treatment response should be scheduled.

Side Effects

Beyond the effects of the surgery itself, brachytherapy can cause both acute and long-term side effects. Comparatively speaking, these tend to be far less profound than with EBRT.

Fatigue is the most common short-term side effect lasting for one or several days. Less commonly, there may be a generalized soreness in the treated breast. A mild pain reliever like Advil (ibuprofen), Aleve (naproxen), or Tylenol (acetaminophen) can usually ease breast tenderness.

In some cases, the implantation of the catheter can cause a seroma, a pocket of fluid beneath the skin that may require drainage with a needle as well as oral antibiotics.

Long-term side effects are less common but may include a change in skin texture and color, skin dryness, and a loss of hair under the arm. Moisturizing the skin can usually help.

You may also experience the swelling of an arm if brachytherapy was performed near the axillary lymph nodes in the armpit. Known as lymphedema, the condition will usually be mild and resolve on its own without treatment. Call your doctor if the condition persists or worsen.

Contraindications

Breast brachytherapy is not for everyone. Although most women with breast cancer will benefit from lumpectomy and EBRT, only a subgroup are appropriate candidates for breast brachytherapy. Some of the contraindications include:

  • Pregnancy
  • Stage 3 or stage 4 breast cancer
  • Having bilateral breast cancer (cancer in both breasts)
  • Having had cancer in the opposite breast
  • Having had other cancers (with the exception of skin cancer and certain gynecological cancers)
  • Paget's disease, which disrupts the replacement of bone tissue
  • Certain connective tissue or collagen disorders
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