The Who, What, Where, When and Sometimes, Why.

Radiation Therapy

Standard radiation therapy (also called radiotherapy) uses targeted, high-energy X-rays or other forms of radiation to kill cancer cells.

The goal of radiation therapy is to kill any cancer that might be left in the breast or nearby lymph nodes after breast cancer surgery.

Radiation therapy is an option for many people who have:

Radiation therapy is standard treatment for most people who have:

Learn about emerging areas in radiation therapy.

Radiation therapy and DCIS

Radiation therapy is often recommended for people who are treated with a lumpectomy (also called breast-conserving surgery) for DCIS.

In rare cases, radiation therapy is recommended after a mastectomy for DCIS.

Learn more about treatment for DCIS.


For a summary of research studies on a lumpectomy plus radiation therapy in the treatment of DCIS, visit the Breast Cancer Research Studies section.

Radiation therapy and invasive breast cancer

After a lumpectomy

Radiation therapy is usually recommended after a lumpectomy.

Radiation therapy can lower the risk of [3]:

  • Breast cancer recurrence (a return of cancer) in the treated breast
  • Breast cancer death

Some women 65 and older who have small, lymph node-negative invasive breast cancers that are HER2-negative and estrogen receptor-positive (and who will get hormone therapy) may be able to avoid radiation therapy after a lumpectomy [10-11].

After a mastectomy

Some people who have a mastectomy will not need radiation therapy.

However, in some cases, radiation therapy is used after a mastectomy to treat the chest wall and lymph nodes. These can include the axillary lymph nodes (lymph nodes in the underarm area) and the internal mammary nodes (lymph nodes around the collarbone or near the breastbone).

Click on the topics below to learn more.


Radiation therapy is carefully planned and precisely given. Your treatment is tailored to your breast cancer and your body.

Learn about planning and treatment sessions for radiation therapy.

Radiation therapy has some short-term side effects (such as skin redness and tenderness) and for some people, long-term side effects (such as lymphedema).

Before you begin radiation therapy, talk with your health care provider about possible side effects and how to manage them.

Learn more about possible side effects of radiation therapy.

It’s important to follow the treatment plan prescribed by your health care provider in terms of:

  • Timing
  • Dose
  • Frequency

People who complete their full recommended course of treatment have a higher chance of survival.

Completing radiation therapy

Radiation therapy after a lumpectomy lowers the risk of breast cancer recurrence and may increase the chances of survival [3]. It’s usually recommended after a lumpectomy and is sometimes given after a mastectomy.

Radiation therapy for early breast cancer most often involves treatment once a day, 5 days a week, for 1-6 weeks.

Getting to and from the treatment center every day for weeks can be hard, especially if you live far away or if others rely on you for care. It’s OK to ask for help. It’s important to complete your radiation therapy without gaps or delays.

There may be resources available if you need a ride to and from radiation therapy or help with childcare or eldercare. Family and friends often want to help but don’t know how. These are great ways for them to get involved.

There may be some programs that help with local or long-distance transportation and lodging (if you need a place to stay overnight during treatment).

There may also be programs to help you with childcare or eldercare costs.

Learn more about transportation, lodging, childcare and eldercare assistance programs.

Learn more about the importance of following your breast cancer treatment plan.

Find other resources that offer social support and practical support.

Komen Financial Assistance Program

Susan G. Komen® created the Komen Financial Assistance Program to help those struggling with the costs of breast cancer treatment by providing financial assistance to eligible individuals.

To learn more about this program and other helpful resources, call the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877-465-6636) or email

Se habla español.

Not everyone can have radiation therapy. Being pregnant, having certain health conditions or having certain inherited gene mutations can increase the side effects of radiation therapy.

  • Pregnancy. Radiation can harm a fetus. Depending on the timing of the pregnancy and the breast cancer diagnosis, you may be able to have a lumpectomy and wait until after delivery to have radiation therapy.
  • Scleroderma. Radiation therapy can cause harm to normal tissue during and after treatment in people who have scleroderma. In some women at higher risk of breast cancer recurrence, radiation therapy may still be used.
  • Some inherited gene mutations. Radiation therapy can cause harm to normal tissue during and after treatment in people who have certain rare, inherited gene mutations. In some women at higher risk of breast cancer recurrence, radiation therapy may still be used. In addition, some women with certain gene mutations may be at a higher risk of a new breast cancer in the future. Sometimes these women choose to have a mastectomy to avoid radiation therapy and lower this risk.
  • Past radiation therapy to the same breast. In general, radiation therapy to the breast can only be given once. However, repeat radiation to the chest is sometimes recommended in the treatment of breast cancer recurrence. And, some data suggest repeat radiation therapy to a portion of the breast may be a reasonable option for certain women who had a lumpectomy for breast cancer in the past [4].

Women with breast implants (saline or silicone) can usually have radiation therapy. However, radiation therapy can impact the cosmetic look and the long-term viability of the implant (whether the implant will fail and need to be removed).

Side effects of radiation therapy on breast implants

Radiation therapy can cause scarring and hardening of the implant, leading to a poor cosmetic look and/or chronic pain in the breast area. In these cases, the implant may need to be removed.

Radiation therapy and breast reconstruction with implants

If your treatment plan includes a mastectomy, radiation therapy and breast reconstruction, discuss possible risks with your plastic surgeon and radiation oncologist.

Learn more about breast reconstruction.

New radiation therapy methods are under study in clinical trials.

Learn about emerging areas in radiation therapy

Learn more about clinical trials.

  • Why do you recommend radiation therapy for me?
  • Is there a clinical trial I can join?
  • How will radiation therapy affect my risk of a local breast cancer recurrence, metastasis or a new breast cancer? Please explain the differences.
  • How long will each treatment session take? How many sessions will I have?
  • When will I begin radiation therapy? Can I choose the days and times of treatment?
  • Can I have accelerated (shortened course) whole breast radiation therapy?
  • Can I come to treatment sessions alone, or should a friend or family member come with me?
  • What clothes should I wear to the treatment sessions?
  • Can I wear deodorant to the treatment sessions?
  • What lotion, soaps or other skincare products should I use or avoid during the course of treatment?
  • Can I wear a bra during the course of treatment?
  • What side effects should I expect? How long might they last? Which side effects need medical care?
  • What problems should I report to you right away?
  • What are the long-term risks of radiation therapy?
  • Who do I contact if I have problems or questions about my treatment? What about on weekends or holidays?
  • What precautions should I take during treatment?
  • Can I continue normal activities? Are there activities I should avoid, such as taking a bath, swimming or going in a hot tub?
  • Where can I find a support group for people who have breast cancer (or people who have any type of cancer)?
  • Should I continue to see my regular doctor or gynecologist during my treatment?
  • How often will I have check-ups and follow-up tests after treatment ends? Will a follow-up care plan be prepared for me?
  • Which health care provider will oversee my follow-up care?
  • Who can talk with me about the cost of my treatment (including the expenses covered by my insurance and the costs I should expect to pay out-of-pocket)?

Learn more about talking with your health care team.

If you’ve been recently diagnosed with breast cancer or feel too overwhelmed to know where to begin to gather information, Susan G. Komen® has a Questions to Ask Your Doctor About Radiation Therapy and Side Effects resource that might help.

You can download and print it to take with you to your next doctor’s appointment or you can save it on your computer, tablet or phone using an app such as Adobe. Plenty of space and a notes section are provided to write or type the answers to the questions.

You can download, print and write on the resource at your next doctor’s appointment or you can save it on your computer, tablet or phone using an app such as Adobe. Plenty of space and a notes section is provided to write or type the answers to the questions.

There are other Questions to Ask Your Doctor resources on many different breast cancer topics you may wish to download.


Treatment guidelines

Although the exact treatment for breast cancer varies from person to person, evidence-based guidelines help make sure high-quality care is given. These guidelines are based on the latest research and agreement among experts.

The National Comprehensive Cancer Network (NCCN), the American Society of Clinical Oncology (ASCO) and the American Society for Radiation Oncology (ASTRO) are respected organizations that regularly review and update their guidelines.

In addition, the National Cancer Institute (NCI) has treatment overviews.

Talk with your health care team about which treatment guidelines they follow.

After you get a recommended treatment plan from your health care team, study your treatment options. Together with your health care team, make thoughtful, informed decisions that are best for you. Each treatment has risks and benefits to consider along with your own values and lifestyle.

You’re not alone

If you’re facing radiation therapy, it’s normal to feel worried or scared about going through treatment and the side effects you may have. Many people have been where you are today. They had the same fears. They’ve gone through breast cancer treatment and are living their lives.

Sharing experiences and advice with others going through radiation therapy or those who’ve finished treatment may help. You can do this in a support group or by connecting one-on-one with another breast cancer survivor.

You can also talk with your health care providers about how you’re coping. They care about your overall well-being and can help you find ways to improve it. In addition to suggesting a support group, they may connect you to another member of your health care team, such as a social worker or patient navigator, for support. They may also refer you to a counselor.

Emotional health after radiation therapy

After going through radiation therapy, you may feel a buildup of emotions. You may have been anxious leading up to it and afterward, you may feel a sense of relief or you may be worried about what happens next. This is normal.

Make sure you take time to recover both emotionally and physically. You may want to have family and friends available for support.

Our Support section has list of resources for finding local and online support groups and other resources.

Learn more about social support and support groups.

Learn about healthy ways to cope with stress.

Susan G. Komen® Support Resources

  • Do you need help? We’re here for you. The Komen Patient Care Center is your trusted, go-to source for timely, accurate breast health and breast cancer information, services and resources. Our navigators offer free, personalized support to patients, caregivers and family members, including education, emotional support, financial assistance, help accessing care and more. Get connected to a Komen navigator by contacting the Breast Care Helpline at 1-877-465-6636 or email to get started. All calls are answered Monday through Thursday, 9 a.m to 7 p.m. ET and Friday, 9 a.m. to 6 p.m. ET. Se habla español.
  • The Komen Breast Cancer and Komen Metastatic (Stage IV) Breast Cancer Facebook groups are places where those with breast cancer and their family and friends can talk with others for friendship and support.
  • Our fact sheets, booklets and other education materials offer additional information.

Updated 04/12/24