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

Going Through Radiation Therapy

Radiation therapy can harm normal tissue, so it’s carefully planned and precisely delivered. This helps ensure the radiation kills as many cancer cells as possible while doing as little injury as possible to other parts of your body.

Radiation therapy is planned specifically for your breast cancer, the shape of your body and your internal anatomy. This is why sessions can’t be split between different treatment centers.

Your treatment plan is based on:

  • The tumor size, type and location
  • The number of lymph nodes with cancer
  • The type of breast surgery (and lymph node surgery) you had
  • The shape of your breast or chest wall, and the shape and location of nearby organs (such as your heart and lungs)

Planning session

Your radiation oncologist oversees the radiation planning session.

You will lie on a special table while your radiation oncologist decides the proper dose of radiation and where to give the radiation. They will use a CT scan to guide the radiation planning.

During the planning session, your radiation oncologist will put small marks (about the size of a pinhead) on your skin.

These marks ensure you are correctly positioned for each treatment. They may be ink spots, or they may be permanent tattoos. If they are ink spots, don’t wash them off until you finish all of your radiation therapy.

You may be asked to hold your breath during the planning session. This is one way to minimize radiation exposure to the heart.

Radiation therapy sessions

Your radiation oncologist leads a team of technicians and nurses. The team will work with you at each radiation therapy session.

What should I expect?

During each session, you will lie on a special table.

You may be asked to hold your breath while the radiation is given. This is one way to minimize radiation exposure to the heart.

If lymph nodes were removed during surgery and contained cancer, often the area near the lymph nodes is also treated with radiation.

Each session lasts about 10-20 minutes. Most of this time is spent positioning your body to ensure the treatment is given exactly as planned.

With any standard radiation therapy (whole-breast radiation therapy, accelerated, hypofractionated whole-breast irradiation, partial breast irradiation or a boost) you will not be radioactive when you leave the radiation treatment center. You will not pose any radiation risk to your family or your pets.

How often will I go for treatment?

Treatment is most often given once a day, 5 days a week, for 3-6 weeks.

The schedule of radiation sessions is designed to treat your breast cancer and varies from person to person.

Many women now get a shortened course (5 days a week, for 3-4 weeks) of radiation therapy [7]. This is called hypofractionated whole-breast irradiation.

It’s like standard whole-breast radiation therapy except it uses a slightly higher dose of radiation per session (hypofractionation). This reduces the number of treatment sessions, making the overall course shorter.

For most women with early breast cancer, hypofractionated whole-breast irradiation is as effective as standard whole-breast radiation therapy [7].

After radiation therapy to the whole breast, you may have more radiation (called a boost) to the part of the breast that had the tumor.

This boost increases the amount of radiation given to the area at highest risk for breast cancer recurrence.

Your boost radiation session is similar to a regular session. 

Radiation therapy often delivers radiation to the whole breast. Partial breast irradiation delivers radiation only to the area around the tumor bed (the space where the tumor was removed during lumpectomy).

It’s typically done in a shortened course over only 5-10 days. This reduces the number of treatment sessions. It can also be done over 3-4 weeks, similar to whole breast radiation therapy, or may be done at the same time as surgery.

Partial breast irradiation is an appropriate treatment for select people with early-stage breast cancer [7].

Talk with your radiation oncologist about whether you might be a good candidate for partial breast irradiation. Discuss the pros and cons of partial breast irradiation compared to whole breast radiation therapy.

Methods of partial breast irradiation include:

  • Brachytherapy uses targeted radiation placed inside the tumor bed. Implanted radiation “seeds” (interstitial radiation therapy) or a single small balloon device (intracavitary radiation therapy) can be used to deliver the radiation.
  • External beam radiation therapy uses standard external beam radiation therapy, but only targets the tumor bed.
  • Intraoperative radiation therapy gives a single dose of radiation to the tumor bed during a lumpectomy. This dose of radiation is higher than in a standard radiation session. Check with your insurance company before getting intraoperative radiation therapy, as this type of partial breast irradiation may not be covered.

When your treatment plan includes chemotherapy

Radiation therapy is usually given after chemotherapy. However, you can get partial breast irradiation before chemotherapy (if your treatment plan includes chemotherapy).

Things to remember while going through radiation therapy

Things to remember

  • Don’t wash the ink marks off your skin.
  • Check with your radiation therapy team before putting any lotions or powders on the treated area.
  • Wear clothing that’s easy to take off in case you need to change into a hospital gown.
  • Use reliable birth control to prevent pregnancy (radiation can harm a fetus). Discuss the best form of birth control with your health care team.
  • Keep the treated area out of the sun.
  • Don’t put anything very hot or very cold (like a heating pad or an ice pack) on the treated area.
  • Tell your health care team about any side effects.

Adapted from National Cancer Institute materials [9].


Transportation, lodging, child care and elder care assistance

If you don’t live near the radiation treatment center, it can be hard to get to and from therapy sessions.

Sometimes, there are programs that help with local or long-distance transportation and lodging.

There are also programs to help you with child care and elder care costs.   

Learn more about transportation, lodging, child care and elder care assistance programs


  • If you or a loved one needs more information about breast health or breast cancer, call the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877-465-6636). All calls are answered by a trained specialist or oncology social worker in English and Spanish, Monday through Friday from 9:00 a.m. to 10:00 p.m. ET. You can also email the helpline at
  • We offer an online support community through our closed Facebook Group – Komen Breast Cancer group. The Facebook group provides a place where those with a connection to breast cancer can discuss each other’s experiences and build strong relationships to provide support to each other. Visit Facebook and search for “Komen Breast Cancer group” to request to join the closed group.
  • Our fact sheets, booklets and other education materials offer additional information.


Updated 06/30/21