University of California San Francisco
Helen Diller Family Comprehensive Cancer Center

Complications of Breast Radiation

Breast Care Center Banner

What are the possible complications?

The short-term and long-term complications of breast radiation therapy are unusual but sometimes do happen. Because of this, it is important for you to know about any potential problems. Your doctor will talk to you about the potential of these risks happening in your particular case. These potential problems include:

Common issues:

  • Permanent loss of hair under the arm on the side of treatment.
  • Possible increase in fatigue that is temporary. Some people do not experience fatigue while others do. It can sometimes take several months to resolve.
  • Darker skin or change in the feeling of the breast. The skin of your treated breast may appear to have a slightly darker pigment or feel a bit firmer than the nontreated breast. The areola (area around the nipple) may change in color as well.

Uncommon issues:

  • A spontaneous rib fracture in the area treated. The ribs under your breast will receive some dose of radiation during your treatment. This can make the bone more brittle. Rib fractures are rare and heal like any other fracture. The rib won't usually break on its own. It usually happens if you have an accident like a fall or have a car accident.
  • Development of a rare cancer called sarcoma many years in the future.
  • Cancer in the opposite breast. Some particles of the radiation may reach your other breast. This is called scatter. The dose of radiation your other breast will receive is minimal.
  • Development of lung cancer. The risk of this is reduced if you do not smoke.

If you receive treatment that includes the lymph-bearing areas (supraclavicular area):

  • A nerve injury called brachial plexopathy on the treated side. This appears as a sensation of pins and needles in the affected arm and possibly some weakness. It may occur with radiation to the lymph nodes.
  • Irritation of the lung called pneumonitis. This is like pneumonia but is treated differently. It is not caused by infection.
  • Lymphedema. This is swelling or fluid retention within your arm. The risk of swelling is increased with removal of your lymph nodes during surgery. Excessive heat and weight gain are also risk factors in developing lymphedema.

If you receive treatment to the left breast or left chest wall after mastectomy:

There may be a small risk of heart problems years later, above baseline risk.

Note: The information above was reproduced from the UCSF Radiation Oncology website at