Breast Cancer Radiation Side Effects

If someone is diagnosed with breast cancer, radiation therapy is likely to be part of their treatment plan. Radiation therapy consists of high beams of energy directed at cancer cells to kill them. Side effects of radiation can include skin changes and feeling tired.

Today's radiation therapy is more advanced than earlier forms of radiation therapy that were known to cause lasting cell or organ damage, but risks exist and should be discussed with your healthcare provider.

This article will review the side effects of radiation for breast cancer and discuss the types and benefits of radiation therapy. 

Person receiving radiation treatment for breast cancer

Mark Kostich / Getty Images

What Is Radiation Therapy?

Radiation therapy is a commonly used therapy for many types of cancer. For breast cancer, radiation is typically used after surgery to help reduce the risk of cancer returning. It can also help treat a symptom, such as pain, in someone with cancer that has spread outside the breast.

During treatment, a dose of ionizing radiation is targeted at the tumor. It is often given each day, Monday through Friday, for one to six weeks. Each dose of radiation is referred to as a fraction.

Radiation damages the DNA (genetic material) inside the cells it's hitting, which causes the cell's death. Unfortunately, radiation can also damage healthy cells, leading to side effects. Some body tissues can handle radiation better than others, so side effects may occur quickly or appear later, even after radiation is done. 

Types of Radiation Therapy

The most common type of radiation therapy for breast cancer is called external beam radiation therapy (EBRT). During EBRT, a machine outside of the body delivers the radiation to the prescribed area of the body.

The exact type that is right for you will be based on many factors, including:

Whole Breast Radiation

In whole breast radiation, the whole breast (and possibly lymph nodes) are treated with radiation. This generally happens after surgery such as a lumpectomy, when the cancerous tumor is removed.

Radiation is given to treat the entire breast to help prevent breast cancer from coming back in that breast. This type of radiation is often given for five to six weeks.

Accelerated Breast Radiation

There are different types of accelerated breast radiation, and not everyone who needs radiation is eligible for accelerated radiation. This type of radiation usually is for those who have breast cancer that was diagnosed at an early stage and is used after a lumpectomy, when the tumor was cut out of the breast. There are multiple ways of giving accelerated breast irradiation.

For some, the whole breast is treated for a shorter amount of time, but with a higher dose of radiation. It is usually given once a day for a total of five days.

For others, instead of treating the entire breast, partial breast irradiation targets the area where the tumor was removed and a smaller area around it. This type of radiation can decrease the risk of radiation damage to the heart, ribs, lungs, and shoulder.

Another method of accelerated radiation is the use of brachytherapy. During this procedure, a balloon is placed into the cavity left behind after the lumpectomy. The balloon is filled with liquid and left in the breast for a few days.

Twice a day for five days, radioactive seeds are placed into the balloon and removed. The balloon is removed after treatment is over. An example of this is system is called MammoSite.

Radiation Now vs. Then

Previously, the risks associated with radiation therapy were higher, but the delivery systems have improved. The newer ways to administer radiation provide more precise treatment. This has allowed using higher doses of radiation while sparing healthy tissues.

Common Short-Term Side Effects

Short-term side effects may be experienced with radiation therapy.

Side Effects

Any time radiation is given, there is a risk for developing side effects. Because radiation doesn’t only affect cancer cells, the DNA in healthy cells can be damaged. The most common side effects that occur for radiation to the breast include:

  • Dermatitis: Irritation to the skin that can cause discomfort, rash, or peeling
  • Fatigue
  • Swelling to the breast getting radiated
  • Breast pain 

Who’s at Risk?

Anyone who receives breast radiation will be at risk for developing any of the above side effects. There is potential for radiation to injure skin cells in the targeted area. Feeling tired, especially as treatment continues, can happen to anyone getting radiation. 

Rare Short-Term Side Effects

It is possible that less common side effects could occur with radiation therapy.

Side Effects

Rare short-term side effects include inflammation of deeper tissues in the chest, such as the lungs, heart, or esophagus (food tube).

  • Pneumonitis: Inflammation of healthy lung tissue that can cause shortness of breath and cough
  • Pericarditis: Inflammation of the heart that can cause palpitations, shortness of breath, chest pain, and cough
  • Esophagitis: Inflammation of the esophagus, the tube that moves food from the mouth to the stomach, which can cause chest pain, feeling of food getting stuck, and difficulty swallowing

Who’s at Risk?

Pneumonitis can happen to anyone getting radiation to the breast, as the lungs sit behind the breast tissue. The risk for pericarditis is highest for those treated with radiation to the left breast. The risk of esophagitis exists for anyone getting radiation to the breast.

Possible Long-Term Side Effects

Although some side effects occur quickly, damage to cell DNA can cause long-term side effects and problems later in life.

Side Effects

The most common long-term side effects of radiation for breast cancer include:

  • Fibrosis: The skin of the breast can become thickened and hard and potentially alter the shape of the breast. 
  • Lymphedema: When radiation is given to lymph nodes, the flow of the lymph fluid can be altered, which causes significant swelling to the extremity that’s been affected. The swelling can be a lifelong problem. 
  • Heart disease: Radiation that injures the heart can cause an increased risk of having a heart attack later in life. It can also cause a condition called cardiomyopathy, which is a weakening of the heart muscle. 
  • Damage to the nerves: Known as brachial plexopathy, the nerves in the brachial plexus are damaged by radiation, which can cause a lot of pain and weakness to the affected arm.

Who’s at Risk

Those who receive radiation to the left breast are at highest risk for developing heart problems later in life. If anyone receives radiation to the lymph nodes, they are at risk for lymphedema. All who receive radiation to the breast are at risk for fibrosis.

Risks vs. Benefits

The risks associated with radiation for breast cancer treatment are certainly something to be aware of when making treatment decisions for breast cancer. It’s important to weigh the risks of radiation with the benefit of treatment.

Radiation is given with the intent of treating breast cancer. Not treating it may have the risk of it coming back or spreading to other areas of the body.

Discussing your personal situation with an oncologist (physician who specializes in cancer diagnosis and treatment) can help determine your personal risk for breast cancer returning. They can review with you how likely it will be for radiation to cause short-term or long-term side effects.

Managing Side Effects

Side effects of breast cancer radiation can be managed (typically, the earlier, the better). Your radiation oncologist (physician specializing in treating cancer with radiation therapy) can give you specific instructions regarding your treatment. General side effect management can include the following:

  • Skin: Keeping skin protected from the sun is important. Moisturize your skin with a lotion or cream approved by the radiation oncologist. This can help your skin feel more comfortable when it is irritated by radiation.
  • Fatigue: Fatigue can be managed by ensuring adequate sleep at night. Getting activity and exercise during the day is also important. Do group activities at the time of day you have the most energy.

Discuss any side effects you notice with the radiation treatment team. They can help you determine the best way to treat whatever side effect you’re experiencing. Ask what symptoms may indicate long-term or rare side effects.


Radiation is commonly used as part of the treatment plan for breast cancer. Radiation therapy damages the DNA of cancer cells and can also damage healthy cells. Short-term side effects can include skin irritation, swelling, and fatigue. Long-term side effects can include fibrotic changes to the breast, heart and lung damage, and lymphedema. 

A Word From Verywell 

Radiation is an important part of breast cancer treatment. Before starting treatment, talk with your radiation oncologist about any concerns you have. Be proactive in preventing and managing side effects so you have a successful treatment with minimal side effects.

Frequently Asked Questions

  • How long do side effects of radiation for breast cancer last?

    The short-term side effects from radiation generally last two to four weeks before resolving. Long-term effects that occur from radiation can last indefinitely.

  • What is the worst side effect of radiation?

    The worst side effect of radiation may be different for each person. It can depend on how severe the side effects are. Some side effects, if severe, can potentially cause permanent problems with heart and lung function.

  • Will radiation kill breast cancer?

    Radiation can kill breast cancer. Radiation causes damage to the DNA inside cancer cell, which causes it to die. The damage to the DNA also prevents the cells from replicating and making more copies of themselves.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Goldberg M, Whelan TJ. Accelerated partial breast irradiation (APBI): where are we now? Curr Breast Cancer Rep. 2020;12(4):275-284. doi:10.1007/s12609-020-00384-x

  3. National Cancer Institute. MammoSite.

  4. Chen HHW, Kuo MT. Improving radiotherapy in cancer treatment: promises and challengesOncotarget. 2017;8(37):62742-62758. doi:10.18632/oncotarget.18409

  5. American Society of Clinical Oncology. Side effects of radiation therapy.

By Julie Scott, MSN, ANP-BC, AOCNP
Julie is an Adult Nurse Practitioner with oncology certification and a healthcare freelance writer with an interest in educating patients and the healthcare community.