By Carol L. Kornmehl, MD
Attending Radiation Oncologist, The Valley Hospital, Ridgewood, New Jersey

People often think radiation therapy causes burns of the skin. Although this is true for certain types of radiation therapy, it is not universally true.

If and when a skin reaction was to develop, it is generally not until the third week of radiation therapy. Skin reactions, ranging from redness of the skin, darkening, peeling, itching, tenderness, blistering, and ulceration/burns, are more common in people who undergo radiation therapy with a more shallow radiation beam, such as that commonly used to treat skin cancer, breast cancer, and head and neck cancers.

However, the more penetrating beam typically used to treat cancers of the pelvis and abdomen rarely results in a skin reaction. And skin reactions are occasionally encountered when the chest area is irradiated.

Skin reactions from radiation therapy are limited to the treated area. Most radiation therapy is delivered through two or more treatment fields. For example, the chest is often treated from both the front and the back. Spreading the radiation beams to more than one area reduces the likelihood of a skin reaction because each beam is less concentrated than one single beam.

The use of a single radiation beam, as is common in the treatment of skin cancers, is more likely to result in a skin reaction.

Bolus, a flabby, rubbery material, is used in certain situations to “fool” the radiation beam so it will deposit the maximum dose on the skin surface instead of a fraction of an inch deeper, as it would otherwise. Therefore, a skin reaction is almost inevitable in this scenario. Bolus is usually incorporated into radiation therapy for skin cancers or when a surgical scar, such as a mastectomy scar, needs to receive a full dose of radiation therapy.

People who have received chemotherapy shortly before or during radiation therapy are more susceptible to a skin reaction. And the higher the dose of radiation therapy, the greater the risk of a skin reaction.

Prophylactic skin care, with the application of moisturizing emollients from the outset of radiation treatment, is prudent. Once a reaction occurs, specific skin care measures are prescribed. Some people require an antibiotic or steroidal cream or ointment. Some also need pain medication until a burn heals.
The good news is that virtually all skin reactions are temporary.

Once they have resolved, the cosmetic appearance of the skin is quite good.

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Watch for Dr. Kornmehl’s Summer issue web-exclusive article “Comparing the Side Effects of Radiation Therapy and Chemotherapy.”