Radiation Therapy for Breast Cancer

Last Modified: March 21, 2016

Radiation therapy is often used to treat breast cancer after surgery. The doses of radiation used to destroy cancer cells can also hurt normal cells. The damage to these normal cells is the cause of the common side effects of radiation treatment. Thus the possible side effects of radiation therapy are directly related to the area of the body being treated. Side effects are caused by the cumulative effect of radiation on the cells; therefore most patients do not experience any side effects until a few weeks into their treatments. While side effects may be unpleasant, there are treatments to help deal with them, and most side effects are temporary, disappearing gradually after therapy is complete.

Most radiation oncologists see their patients at least once a week while the patient is receiving treatment. This visit with the healthcare team serves as an opportunity to ask questions, discuss any side effects, and implement and necessary interventions to help relieve the side effects. However, you can report concerning symptoms anytime to the treatment team.

Short Term Side Effects

The following list includes some of the most common side effects of radiation therapy for breast cancer. Remember that the treatment can affect each patient differently and you may not experience these concerns. Talk with your radiation oncologist and health care team about what you can expect from your specific treatment.

  • Skin irritation: Your skin may become red, irritated, dry, or sensitive. This may progress to look like a sunburn. Treat the skin gently to avoid further irritation, and bathe carefully using only warm water and mild soap. Avoid perfumed or scented lotions or soaps, as these may cause further irritation. Avoid sun exposure, which can worsen the irritation.
  • Mild to moderate breast swelling during treatment. In some women, the breast becomes smaller and firmer after radiation therapy. Changes to the breast tissue and skin usually go away in six to 12 months.
  • Mild fatigue that generally improves a month or two after treatment ends.
  • Some patients experience mild tenderness in the breast or chest wall.
  • Some patients experience swelling to the ipsilateral arm (the arm that's closest to the area being treated) that may result in a reduced range of motion. Any swelling should be brought to the attention of your oncology team.
  • Reduced blood counts, including neutropenia (low white cell count), anemia (low red cell count) or thrombocytopenia (low platelet count).

Long-Term Side Effects

The side effects discussed thus far tend to occur during treatment, up until a few months after treatment. Long-term effects can occur months to many years after cancer treatment and the risks vary depending on the areas included in the field of radiation and the radiation techniques that were used, as these continue to develop and improve.

Though the risk is low, you should be aware of these possible long-term effects:

  • There is a low risk of developing a second cancer in or near the radiation field. These are called secondary cancers, and they develop as a result of the exposure of healthy tissue to radiation. Modern radiation techniques are designed to limit this exposure, but it is not always possible to prevent all exposure and still achieve the desired outcomes.
  • Radiation to the breast, chest wall or reconstructed breast may cause permanent changes in the skin, including a darkening or "tanning" or fibrosis, a thickening or scarring of an area of tissue in the breast.
  • There can be damage to the nerves, leading to pain or loss of strength or feeling in the arm, on the side that was treated.
  • Damage to the drainage (lymphatic) system in the area can lead to a chronic swelling, called lymphedema. Risk of lymphedema is highest for patients who also had surgical lymph node dissections and, to a lesser extent, sentinel node biopsy. A survivor with lymphedema who develops pain or redness in the arm, especially with fever, should be evaluated right away, as these signs may indicate infection.
  • Survivors of breast cancers, particularly left-sided breast cancers, may be at increased risk for developing cardiac (heart) complications.
  • There is a risk of scarring of the lung under the treated breast, though this does not typically cause any symptoms.

After treatment, talk with your oncology team about receiving a survivorship care plan, which can help you manage the transition to survivorship and learn about life after cancer. You can create your own survivorship care plan using the OncoLife Survivorship Care Plan.


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