Radiation therapy is a treatment that uses high-energy x-rays to destroy cancer cells. Radiation therapy is a local treatment targeted at the breast and sometimes the surrounding lymph node area to destroy any stray cells that may have been left behind to reduce the chance of a recurrence. It is sometimes also given after a mastectomy, but only if there is a high risk of a local recurrence.
Patients who need systemic therapy, such as chemotherapy, may receive their radiation after chemotherapy is completed. The oncologist, breast surgeon, radiation therapist, and plastic surgeon (if reconstruction after mastectomy is planned) will work together to decide the best sequence of treatments.
Prior to treatment, in a process called simulation, the radiation oncologist designs a specific and individualized treatment for the patient, using a special CT scanner to image her in the same position that will be used for the course of radiation therapy. Using the imaging data, the radiation oncologist works closely with a medical physics team to choose beam directions that target the area at risk without exposing nearby healthy organs such as the lungs and heart to significant radiation. The patient's skin may be marked with tiny tattoos so each treatment can be aimed at precisely the same region. A special mold may also be made to help the patient to get into exactly the same position for each treatment.
Once this plan has been finalized, the patient starts her course of therapy, coming five days each week for four to six weeks. At each session, which generally lasts about 15 minutes, the patient will lie on a table on her back. For women who have very large breasts, a special table may be used. The woman lies face down on this table, placing her breast through an opening in the table, and the treatment is given from below.
Newer forms of radiation therapy for breast cancer include:
- Intensity-modulated radiation therapy (IMRT), in which a computer program is used to deliver a uniform, or homogenous, dose to the breast. In special situations, IMRT is also used to limit the radiation dose to organs close to the breast or lymph nodes being treated.
- Radiation delivered in the prone position, in which the patient lies on her stomach instead of her back, and radiation is directed to the affected breast as it hangs through an opening in a special table. This approach reduces radiation exposure to nearby vital organs such as the heart and lungs.
- Image-guided radiation therapy, which enables doctors and radiation therapists to locate the target before the radiation dose is given while the patient is in the treatment position, using implanted clips or bone landmarks for guidance.
- Partial breast irradiation, an investigational approach for women with very early disease, in which radiation is delivered only to the region of the breast where the tumor was removed.
Side Effects
Radiation treatments today are very precise, and there is little harm to surrounding skin or tissues. The treatments are generally very well tolerated, but after the third week or so there may be some side effects, such as a sunburn-like effect on the skin, fatigue, discoloration of the skin, or swelling and heaviness in the breast. In some women the breast becomes smaller and firmer. Some of these effects wear off, while others may last a few months.
