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 harm 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. Your radiation oncologist 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.

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 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?

Your schedule of radiation sessions is designed to treat your breast cancer. So, schedules vary from person to person.

Treatment is most often given once a day, 5 days a week, for 1-6 weeks.

After a lumpectomy, many women now get hypofractionated whole-breast radiation therapy which uses a slightly higher dose of radiation per session. This reduces the number of treatment sessions and shortens the overall course (5 days a week, for 1-4 weeks). Hypofractionated radiation therapy is under study for use after a mastectomy (learn more).

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

A boost increases the amount of radiation given to the tumor bed which is 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 radiation therapy delivers radiation only to the area around the tumor bed (the space where the tumor was removed during a lumpectomy). Partial breast radiation therapy is also called partial breast irradiation.

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

Partial breast radiation therapy is an appropriate treatment for select people with early-stage breast cancer [8].

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

Methods of partial breast radiation therapy 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 part of the breast that had the tumor (tumor bed) and a small area of surrounding breast tissue.
  • 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 radiation therapy may not be covered.

When your treatment plan includes chemotherapy

Whole breast radiation therapy is usually given after chemotherapy. In contrast, sometimes partial breast radiation therapy may be given before 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 (such as 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 [10].

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 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, contact the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877-465-6636) or email All calls are answered by a trained specialist or oncology social worker, Monday through Friday from 9:00 a.m. to 10:00 p.m. ET. Se habla español.
  • Komen Patient Navigators can help guide you through the health care system as you go through a breast cancer diagnosis. They can help to remove barriers to high-quality breast care. For example, they can help you with insurance, local resources, communication with health care providers and more. Call the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877-465-6636) or email to learn more about our Patient Navigator program, including eligibility.
  • Komen Facebook groups provide a place where those with a connection to breast cancer can share their experiences and build strong relationships with each other. Visit Facebook and search for “Komen Breast Cancer group” or “Komen Metastatic Breast Cancer group” to request to join one of our closed groups.
  • Our fact sheets, booklets and other education materials offer additional information.


Updated 05/30/22