Types of Radiation Therapy for Breast Cancer

Radiation therapy, also known as radiotherapy, is one of the treatment tools that can be used to treat breast cancer. It involves the use of ionizing radiation to kill cancer cells. It can also be used in palliative care to improve comfort and quality of life for incurable cancer. Radiation therapy is not used for everyone, and your oncologist can discuss with you whether it is appropriate for your course of treatment.

Not everyone with breast cancer needs radiation therapy. It is generally used in the following circumstances:

• After breast-conserving surgery to kill remaining malignant cells so that cancer does not return
• After a mastectomy if the tumor is larger than 5 centimeters (roughly 2 inches) or if nearby lymph nodes have evidence of cancer
• With stage 4 breast cancer, when cancer has spread (metastasized) from the breast to other organs in the body

Broadly speaking, there are three types of radiation therapy used to treat breast cancer: external beam radiation, brachytherapy (also known as internal radiation therapy), and proton beam therapy. Each has its specific purpose and indications.

This article discusses the different types of radiation therapy for breast cancer and what to know about them.

How It Works

Radiation is used against cancer cells to slow their growth and to kill them. Cancer cells are different from normal cells in several ways. Rather than undergoing apoptosis (programmed cell death) so that old cells can be replaced with new ones, cancer cells survive much longer than healthy cells. Moreover, they multiply at an accelerated rate, allowing them to infiltrate normal tissues.

Radiation therapy works by damaging the cancer cell's DNA (hereditary material). The radiation causes cell death. Beyond the tumor site, radiation can be used to clear cancer from nearby lymph nodes.

To minimize damage to nearby tissues, the affected area will be mapped using a 3D imaging study such as computed tomography (CT). The mapping includes the tumor site, as well as the surrounding tissue margins, where cancer cells border normal ones.

Once mapped, the tumor site can be irradiated from different angles either externally (with ionizing radiation beams) or internally (with encapsulated radioactive materials).

Types of Radiation for Breast Cancer

There are different types of radiation for breast cancer, including external beam radiation, brachytherapy, and proton beam therapy. Knowing more about each one can help ease concerns and reduce stress.

External Beam Radiation

External beam radiation is the most common form of radiation therapy used in breast cancer. The radiation is delivered by a machine that emits a single high-intensity X-ray beam from several directions. The procedure is painless and relatively fast, but it can cause side effects.

The areas of irradiation can vary based on whether you've had a mastectomy or lumpectomy and whether nearby lymph nodes are affected. The guidelines for external beam radiation can be described as follows:

• If you have had a mastectomy and no lymph nodes are involved, radiation would be focused on the chest wall, the mastectomy scar, and the tissues where surgical drains were placed.
• If you had a lumpectomy, the entire breast would likely be irradiated (referred to as whole breast radiation) with an extra boost of radiation to the area where the tumor was removed (i.e., the tumor bed).
• If axillary lymph nodes are involved, radiation may be delivered in the armpit and, in some cases, to the supraclavicular lymph nodes above the collarbone and the internal mammary lymph nodes in the center of the chest.

Radiation can also be used with chemotherapy if a tumor cannot be surgically removed.

External beam radiation treatments would start after you heal from breast surgery or complete chemotherapy. The entire schedule of radiation therapy (called the course) is divided into daily treatments referred to as fractions.

Before radiation therapy begins, a radiation oncologist and a radiation therapist will map the treatment area to determine the correct dose and angles of irradiation. The oncologist may apply small ink marks or tattoos to your skin to focus the radiation correctly.

Speak with your oncologist in advance of the procedure to determine if any ink marks will be permanent.

In some cases, accelerated breast irradiation (ABI) or accelerated partial breast irradiation (APBI) may be used. With this treatment, stronger radiation doses are given over a shorter period of time.

There are several types of ABI used when appropriate, including:

• Hypofractionated radiation therapy is used for people who have had a lumpectomy and have no evidence of lymph node involvement. While the procedure is similar to conventional external beam radiation, the dose is higher and the treatment course is reduced to three weeks.
• 3D-conformal radiotherapy involves a specialized machine that only treats the immediate tumor site instead of the whole breast. It is typically used after a lumpectomy in women with no lymph node involvement. Treatment is delivered twice daily for five days.
• Intraoperative radiation therapy (IORT) also involves specialized equipment and is intended for women with early-stage cancer and no lymph node involvement. For this procedure, a single large dose of radiation is delivered immediately after the lumpectomy while the incision is still open.
  

External beam radiation can spill over and affect other tissues, including the lungs, ribcage, and surrounding muscles. It can cause both short- and long-term side effects, depending on the size of the dose, the duration of therapy, the location of the tumor, and your general health.

Common short-term side effects include:

• Fatigue
• Breast swelling
• Skin changes (including redness, darkening, or peeling)

These side effects typically resolve once the therapy is completed, but some may take longer to improve than others. Skin changes, in particular, can take up to a year to normalize and may not fully return to their pretreatment state.

Long-term side effects may also occur due to the cumulative exposure to radiation.

These include:

• Radiation-induced fibrosis: The hardening of breast tissue, which is often accompanied by decreased breast size and difficulty breastfeeding
• Brachial plexopathy: Localized nerve damage, resulting in arm numbness, pain, and weakness
• Lymphedema: Lymph gland obstruction characterized by swelling of the arm and surrounding tissues
• Radiation-induced osteopenia: Localized bone loss, which causes an increased risk of rib fracture
• Angiosarcoma: A rare cancer arising from the cells that line blood or lymph vessels, often a complication of radiation

Brachytherapy

Brachytherapy, also known as internal radiation therapy, is used after a lumpectomy to irradiate the surgical cavity from within. The radiation is delivered through one or several small tubes, called catheters, that are inserted through the skin of the breast. Radioactive seeds, pellets, tapes, or ribbons are then fed into the catheters and left for several minutes or days before being removed.

Brachytherapy can be used with whole breast radiation or on its own as a form of accelerated partial breast irradiation (APBI).

The two types of brachytherapy commonly used in breast cancer are:

• Interstitial breast brachytherapy involves the placement of several catheters in the breast for radiation to be strategically delivered in and around the tumor site.
• Intracavity breast brachytherapy, also known as balloon brachytherapy, is used after a lumpectomy to deliver radiation to the breast cavity via an inflatable balloon filled with radioactive pellets.

Another type of brachytherapy, known as permanent breast seed implant (PBSI), may be used in early-stage cancer. It involves the permanent implantation of low-dose radioactive seeds to prevent cancer recurrence. After several months, the seeds will lose their radioactivity.

As with external beam radiation, brachytherapy requires careful mapping of the surgical cavity. Prior to the delivery of radiation, one or more catheters would be inserted into the breast, either during the lumpectomy or with a separate procedure. The catheters are kept in place for the duration of therapy, with a short length of tubing extending outside of the breast.

The type and dose of radioactive materials (typically iodine, palladium, cesium, or iridium) can vary by the treatment approach. They can range from ultra-low-dose rate (ULDR) seeds used for PBSI to high-dose-rate (HDR) implants commonly used for APBI.

Once the correct dose and coordinates have been established, the external catheter is connected to a machine called an afterloader. This feeds the radioactive source through the catheters and removes them once the fraction is complete.

Intracavity brachytherapy is typically performed over five days and involves two 10- to 20-minute sessions delivered six hours apart. Interstitial brachytherapy, which is less commonly used, may be performed as an in-hospital procedure over one or two days.

Brachytherapy can cause many of the same side effects as external beam radiation, although they tend to be less severe.

Because brachytherapy involves one or more small incisions, there is an added risk of infection, particularly if the catheter site gets wet or is not cleaned. In some cases, a pocket of fluid, called a seroma, may develop beneath the skin. This requires drainage with a needle.

Proton Beam Therapy

Proton beam therapy, also known as proton therapy, is an advanced method of radiation that poses less harm to surrounding tissues. The radiation emitted in proton therapy does not travel beyond the tumor.

The charged particles, called protons, only release their energy as they reach their target. This reduces the amount of radiation that can harm other tissues. Side effects are similar to other types of radiation therapy, but are generally less severe.

The cost and availability of proton therapy remain significant barriers to its use.

Summary

There are different kinds of radiation used to treat breast cancer: external beam radiation, brachytherapy, and proton beam therapy. If you need radiation as part of your treatment plan, the type of radiation can vary depending on the stage of your cancer and other factors.

A Word From VeryWell

Treatment for breast cancer can seem overwhelming or confusing at times. There are many different types of treatment, and different ways of administering each treatment. Your healthcare provider will go over the treatment options that are most appropriate for your diagnosis.

Don't be afraid to ask questions—that's what they're there for. Knowing more about each option can help you discuss the choices and make informed decisions about your care, as well as knowing what to expect.