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Radiation Therapy for Breast Cancer

About Radiation Therapy

Radiation therapy, sometimes referred to as radiotherapy, is a cancer treatment using high doses of radiation, similar to those used in X-rays, to destroy cancer cells (tumors) and stop them from spreading. Radiation damages the genetic material of cells in the area being treated, leaving the cells unable to continue to grow. The procedure itself is painless.

What to Expect

Your doctors are recommending that you receive radiation therapy to your breast or chest wall for treatment of breast cancer. This page gives you information on what to expect with radiation, caring for your skin and ways to minimize side effects during treatment. You will receive a treatment every day, Monday through Friday, over 6 to 7 weeks. During this time, your doctor will examine you at least once a week to monitor for side effects for treatment, and answer any questions and discuss any concerns you and your family may have. If questions or problems arise at other times during the week, your therapist will see you as needed.


Do not wash off the BLACK lines on your skin used to mark your treatment field.  If they begin to fade, the therapists will darken them for you. If you shower, stand with your back to the stream of water.  Use lukewarm water as hot water may be drying to your skin.  If you decide to get small permanent marks, you may wash the treatment area with a mild soap. Wash the treatment area with your hand instead of a washcloth. Dry the treatment area by gently patting with a soft towel instead of rubbing. Be sure to dry the creases of the underarm and under the breast.

Skin Care

Do not use any lotions, creams, oils, deodorant, perfumes or makeup on the breast, chest wall or underarm in the treatment area unless you have checked first with the doctor or therapist.  Some of these products may increase the effect of radiation to the skin. Cornstarch may be used as a substitute for deodorant. It should only be applied to dry skin to prevent caking. Over the course of treatment, you may notice that you perspire less. You may use deodorant on the underarm not receiving radiation therapy. Do not shave the underarm on the treatment side. You may notice some temporary hair loss under the arm in the treatment area. Your skin will be more sensitive to the sun. The treatment area should be covered with clothing when you are outdoors.  If you will be wearing a bathing suit, one with a high neck should protect the treatment area from sun exposure. You may continue your normal skin care routines for the rest of your body.


Your skin will be more sensitive to clothes that rub or are rough in texture (such as wool). Avoid tight-fitting clothes and seams over the bustline when possible. Bras should be supportive without being too tight. If your bra leaves marks on your skin, try a different size or style. Many women find sport or exercise bras more comfortable. Some women prefer not to wear a bra or wear a tube top for light support.

Breast Swelling

You may develop some swelling in your breast from your treatment. This may be somewhat painful but will not interfere with treatment. Wearing a bra or tube top provides support, which may decrease the discomfort. Notify your doctor if you develop pain from swelling or any other type of pain. You may take some mild pain medications such as Tylenol for pain relief, especially at night. Continue to do the arm exercises that you were instructed to do after surgery. The difference in breast size from the swelling should not be noticeable when you are dressed.

Dry Skin

After several treatments, your skin may become dry and itchy. DO NOT RUB OR SCRATCH YOUR SKIN! Cornstarch may help to relieve some of the discomfort. Cornstarch should only be applied to skin without any open areas.

Other Skin Reactions

If you develop a severe reaction with open blisters, report this to our treatment therapist. Dressings and other treatments will be prescribed at that time. If this type of reaction occurs, it will usually appear first in the underarm or in the fold beneath the breast.  More severe skin reactions may require treatment to be postponed for a few days to allow for skin healing. You will still receive the same number of treatments and the same total dose of radiation, but over a slightly longer period of time. A mild pain reliever such as Tylenol may be helpful in decreasing discomfort from this type of reaction. Your therapist will discuss other methods to make you more comfortable. 


Many people feel more tired during their course of radiation. This varies among individuals.  Most women continue to work during treatment with minor changes in their normal routines.  When fatigue occurs, it is usually more severe at the end of the week and seems to improve over the weekend. Activities scheduled in the beginning of the week, when energy levels are higher, may be easier to participate in. Remaining active and doing some regular form of exercise is encouraged during treatment. However, you should not overexert yourself. Be sensitive to your body’s needs.

Self-Breast Exams

You should continue to do monthly self-breast exams on your untreated breast.  If you or any of your family members have any questions about how to do self-breast exams, ask your nurse. When your radiation treatments are completed, you will receive instructions about schedules for follow-up exams and mammograms.

If You Have Questions

If you have any of the side effects listed above, please inform your physician or therapist.  The Radiation Oncology Department numbers are listed below.