Radiation therapy for breast cancer uses high-energy X-rays, protons or other forms of radiation to destroy cancer cells or keep them from growing. It is a local treatment. This means it treats a specific area of the body. Most breast radiation is given as an outpatient treatment, so you can go home after each session.

The radiation given during external beam treatment is painless. You cannot see or feel the radiation, and the treatment does not make you radioactive. It is safe to be around other people after a session.

Radiation therapy for breast cancer may be given in two main ways:

• External beam radiation therapy. A machine directs radiation to the breast, chest wall or nearby lymph nodes. Radiation also may be directed only to the part of the breast where the cancer was removed. Most external beam radiation uses X-rays, also called photons.

  Proton therapy is another type of external beam radiation that may be considered for some people. Proton beams stop after reaching the treatment area, which may reduce radiation exposure to nearby healthy tissue, including the heart and lungs.

• Brachytherapy. Also called internal radiation therapy, brachytherapy places a radioactive source inside the breast near the area where the cancer was removed. It is used in select situations, most often after breast-conserving surgery.

The number of treatments depends on the area being treated, the type of surgery and other details about the cancer. Some people receive five treatments over one week. Others receive about 15 treatments over three weeks. And some may need longer courses. Studies with up to 10 years of follow-up have shown that for many people with early-stage breast cancer, a five-treatment schedule can provide cancer control and long-term side effects similar to those of a 15-treatment schedule.

Radiation therapy often is given after surgery to lower the risk that breast cancer will recur. It may be used after a lumpectomy or, sometimes, after a mastectomy. Radiation therapy also may be used to relieve pain and other symptoms when breast cancer has spread to another part of the body.

Radiation after a lumpectomy

A lumpectomy removes the breast cancer and a small amount of surrounding tissue while leaving most of the breast in place. Radiation therapy usually follows lumpectomy to lower the risk that cancer will return in the treated breast. Radiation may be directed to the whole breast or, for select early-stage cancers, only to the area where the cancer was removed.

Partial-breast radiation may be an option for people whose cancers have favorable features, such as a small size, no lymph node involvement and hormone receptor-positive status. For carefully selected people, partial-breast radiation can often be completed in five or fewer treatments while limiting radiation exposure to healthy tissue.

Some people age 65 and older with small, slow-growing breast cancers may be able to skip radiation after a lumpectomy. This may be an option when hormone therapy is planned and the cancer has not spread to the lymph nodes. Skipping radiation raises the chance that cancer will return in the same breast, but it may not affect how long a person lives. The healthcare team can explain the trade-offs and help decide whether radiation is needed.

Radiation after a mastectomy

A mastectomy removes the entire breast. Radiation is not needed after every mastectomy. Radiation after mastectomy may treat the chest wall or reconstructed breast and nearby lymph nodes. Radiation is more likely to be recommended based on factors such as:

• Cancer found in one or more lymph nodes.
• A large tumor.
• Cancer involving the skin or chest wall.
• Cancer cells found at the edge of the removed tissue.
• How the cancer responded to medicines given before surgery.

Radiation for ductal carcinoma in situ

Ductal carcinoma in situ (DCIS) is stage 0 breast cancer. At this stage, the cancer cells are confined inside a milk duct in the breast. They haven't spread into the breast tissue. Radiation commonly is considered after lumpectomy for DCIS to reduce the risk of cancer returning in the breast. Depending on the size, grade, surgical margins and other features of the cancer, treatment may involve the whole breast or only part of the breast.

Radiation for metastatic breast cancer

When breast cancer spreads to another part of the body, radiation may be used to shrink a tumor and relieve symptoms. For example, radiation can reduce pain from cancer that has spread to the bones. It also may be used for spine metastases that affect movement, bladder or bowel function, or the spinal cord.

Radiation therapy for breast cancer can cause side effects in the treated area. The type and severity of side effects depend on the area treated, the radiation dose, the number of treatments and individual health factors. Most short-term effects improve after treatment ends. Some effects can happen months or years later.

Short-term side effects

Short-term side effects may include::

• Tiredness.
• Skin changes, such as a change in skin color or dryness, in the treated area.
• Swelling of the breast or chest area.
• Hair loss in the treated area, such as the armpit.

Skin changes may look and feel different depending on your skin color. The skin may become pink, red, darker, dry, itchy, sore or swollen. It also may peel. In more-severe situations, the skin may become moist or open up. These changes are sometimes called radiation burns, but the medical term is radiation dermatitis.

The radiation itself does not hurt while it is being delivered. But lying in one position may not be comfortable. The skin and breast also may become sore as treatment continues.

Nausea is not common when radiation is limited to the breast. Radiation is more likely to cause nausea when treatment is directed at the brain, upper abdomen or whole body. Tell your healthcare team if you feel sick during breast radiation so the team can consider other possible causes.

Long-term side effects

Long-term side effects may include:

• Changes in the color or feel of the skin.
• Breast pain or tenderness.
• Changes in breast size, shape or position.
• Swelling of the arm, breast or chest, called lymphedema.
• Lung or heart issues, although modern radiation planning techniques are designed to minimize radiation exposure to these organs.
• A rib fracture, which is rare.
• A second cancer in the treated area, which is rare.

Radiation may make the treated breast look or feel different over time. It may become slightly smaller, firmer or shaped differently from the other breast. The skin also may remain darker or feel thicker. These changes also can be affected by surgery, healing, breast size and the amount of tissue treated.

High blood pressure is not a common direct side effect of radiation therapy to the breast. The healthcare team considers your overall heart health and cardiovascular risk factors, including existing high blood pressure, when planning treatment.

How do side effects compare between five-day and 15-day treatment?

Compared with a 15-day radiation schedule, a five-day schedule uses a larger dose during each treatment. This does not mean that side effects will be more severe. In a large study, an established five-day schedule provided similar cancer control and similar long-term effects on the breast and chest wall compared with a 15-day schedule.

Managing side effects from breast cancer radiation treatment

Your healthcare team checks your skin and asks about other side effects during treatment. Tell the team about symptoms that are new or worse. Early treatment may help keep side effects from becoming more severe.

Skin care during radiation treatment

To help protect the skin in the treated area:

• Wash gently with lukewarm water and a mild cleanser.
• Pat the skin dry instead of rubbing it.
• Avoid scratching or scrubbing the skin.
• Use only creams, lotions, medicines or dressings approved by the radiation therapy team.
• Wear soft, loose clothing that does not rub the treated area.
• Do not place sticky bandages, powders or other products on the treatment area unless the healthcare team says they are safe.

Some products may help prevent or manage radiation-related skin reactions. The best choice depends on the type and severity of the reaction. For example, the healthcare team may recommend a prescription steroid cream, a protective film or a special dressing. Many commonly used products do not work consistently, so check with the radiation therapy team before using them.

Contact the healthcare team if the skin opens up, begins to drain, gets blisters or becomes very painful. Also contact the team if you have a fever or signs of infection.

Before your radiation treatments, you meet with your radiation therapy team, which may include:

• A radiation oncologist, who specializes in treating cancer with radiation. Your radiation oncologist determines the right therapy for you, follows your progress and adjusts your treatment, if needed.
• A radiation oncology medical physicist and a dosimetrist, who make calculations and measurements for your radiation dosage and its delivery.
• A radiation oncology nurse, nurse practitioner or physician assistant, who answers questions about treatments and side effects and helps you manage your health during treatment.
• Radiation therapists, who operate the radiation equipment and give your treatments.

Before you begin treatment, your radiation oncologist reviews your medical history with you and gives you a physical exam to find out whether you would benefit from radiation therapy. The doctor also discusses the potential benefits and side effects of your radiation therapy.

Before external radiation therapy

Before your first treatment, you go through a radiation therapy planning session. This is called a simulation. During the session, a radiation oncologist carefully maps your breast area to target the precise location of your treatment. During the simulation:

• A radiation therapist helps you into the best position to target the affected area and avoid damage to nearby healthy tissue. Sometimes the care team uses pads or other devices to help you hold the position.
• You have a CT scan so that the radiation oncologist can locate the treatment area and healthy tissues to avoid. You hear noise from the CT scanner as it moves around you. Try to relax and remain as still as possible to help ensure consistent, accurate treatments.
• A radiation therapist may mark your body with semipermanent ink or with tiny permanent tattoo dots. These marks guide the radiation therapist in giving the radiation. Take care when washing to avoid scrubbing away ink marks.
• The dosimetrist, radiation oncology medical physicist and radiation oncologist use computer software to plan the radiation treatment you receive. Once the team finishes the simulation, completes the plan and does multiple quality assurance checks, you can begin treatment.

If you have had breast reconstruction or have a breast implant, the radiation therapy team considers this when choosing your position and creating the treatment plan. Planning may involve coordination among the radiation oncologist, breast surgeon and plastic surgeon.

For radiation to the left breast, planning also may include techniques that limit radiation exposure to the heart. For example, the team may plan treatment while you hold a deep breath. This technique is called deep-inspiration breath hold. It moves the heart farther from the treatment area. It can significantly reduce radiation exposure to the heart while keeping effective treatment of the breast.

Before internal radiation therapy

Before you start internal radiation therapy, also called brachytherapy, the care team places a special device in the area where the cancer was removed. This device is for the radioactive material. The team may place the device during your cancer surgery or as a separate procedure several days later.

Radiation therapy usually begins after the surgical area has had time to heal. If chemotherapy is part of your treatment plan, radiation therapy generally begins after you finish chemotherapy. The timing depends on healing, the treatment sequence and the type of radiation planned. You will likely have radiation therapy as an outpatient at a hospital or other treatment facility.

The length of treatment varies. Some people receive five treatments over one week. Others receive about 15 treatments over three weeks. A longer course may be recommended in some situations. Your radiation oncologist recommends a treatment schedule based on your individual needs.

What to wear during radiation treatment

Wear comfortable clothing made from soft fabric. Choose clothing that is easy to remove because you may need to change into a hospital gown. Avoid tight clothing, jewelry, sticky bandages or powder near the treatment area unless the radiation therapy team tells you otherwise.

Treatment schedules

Radiation therapy may be given on different schedules depending on the type of surgery, the area being treated and other details about the cancer.

• Five-day radiation treatment. A five-day course delivers one treatment a day for five days, usually over one week. It may be used to treat the whole breast or chest wall after surgery for select early-stage breast cancers. Some partial-breast radiation schedules also use five treatments or fewer.

  Compared with a 15-day schedule, a five-day schedule uses a larger radiation dose at each treatment. Long-term research has shown that a five-day schedule provides cancer control and long-term effects on healthy breast or chest wall tissue comparable to those of a 15-day schedule. Results remain reassuring after 10 years of follow-up. This supports the use of shorter treatment courses for some people.

• Fifteen-day radiation treatment. A 15-day course usually includes one treatment a day, Monday through Friday, for about three weeks. It is commonly used for whole-breast radiation. It also may be used after a mastectomy or when nearby lymph nodes need treatment.

  Both five-day and 15-day schedules aim to treat the cancer while limiting effects on healthy tissue. Neither schedule is right for everyone. When choosing a schedule, the healthcare team considers the type of surgery, the area being treated, whether lymph nodes are included and other details about the cancer.

• Longer treatment schedules. Some treatment plans take more than three weeks. Your care team may advise a longer course based on the area that needs radiation, whether nearby lymph nodes are treated or whether additional radiation is given to an area at higher risk of the cancer returning.

During external radiation

A typical external radiation therapy session generally follows this process:

• When you arrive at the hospital or treatment facility, you're taken to a special room that's used only for radiation therapy.
• You may need to take off your clothes and put on a hospital gown.
• The radiation therapist helps you into the position you were in during the simulation session.
• The therapist may take images or X-rays to ensure that your position is right.
• The therapist leaves the room and turns on the machine that gives the radiation. The machine is called a linear accelerator.
• Although the therapist isn't in the room during the treatment, the therapist monitors you from another room on a screen. You and the therapist can talk through an intercom. If you feel sick or are not comfortable, tell the therapist. The machine can be stopped at any time.

Delivery of the radiation may last only a few minutes. Most of the appointment is spent placing you in the same position each day to ensure precise treatment.

Radiation therapy is painless. You cannot see, feel, hear or smell the radiation. You may feel some discomfort from lying in the required position, but this generally does not last long.

After the session, you're free to go about your regular activities. External radiation therapy does not make you radioactive. It is safe to be around other people after treatment.

Breast cancer radiotherapy boost

In some situations, the radiation oncologist may recommend a radiation boost. A boost is more radiation directed to the area where the cancer was removed.

A boost usually is given after the main course of whole-breast radiation. Some treatment plans may include it in the treatment schedule. In other plans, a boost may add treatment days. Not everyone needs a boost. The use of a boost may depend on age, the features and surgical margins of the cancer, and the risk that cancer could return in the treated breast.

During internal radiation

For internal radiation, also called brachytherapy, the care team places a radioactive source into the radiation delivery device for a few minutes during each treatment. You will likely get this treatment as an outpatient. The care team takes out the radioactive source before you leave.

When all treatments are done, the care team removes the radiation delivery device. You may get pain medicine before this happens. The area may be sore or tender for several days or weeks as the tissue recovers from the procedure and radiation.

After you complete radiation therapy, your radiation oncologist or another member of the healthcare team schedules follow-up visits. These visits are used to monitor your recovery, check for late side effects and look for signs that the cancer has returned. Make a list of questions you want to ask your healthcare team. Regular follow-up and supportive care can help manage side effects that occur during or after treatment.

Most people slowly return to their usual daily activities during or shortly after radiation therapy. Long-term follow-up helps check recovery, manage ongoing symptoms and support cancer survivorship. The healthcare team can talk with you about any concerns related to fatigue, breast changes, lymphedema, heart health and quality of life after treatment.

Some side effects may continue for a short time after the last treatment. Skin changes, breast tenderness and fatigue often improve with time. Other changes, such as differences in breast firmness, size, shape or skin color, may occur or continue over the months and years after treatment.

After you finish radiation therapy, tell your healthcare team about any new, lasting or worsening symptoms, including:

• Persistent pain.
• A new lump.
• New bruising, rash or swelling.
• A cough or fever that does not go away.
• Weight loss you can't explain.
• Any other symptoms that concern you.