Types of Radiation Therapy for Breast Cancer Treatment
Radiation therapy is used to treat some cases of breast cancer. Radiation is often used to kill any remaining cancer cells after surgery. Radiation therapy damages DNA and kills cells in a particular area (the "field" of radiation). Radiation oncologists can target certain areas with radiation using different radiation techniques. The techniques used depend on the type of surgery and the location and extent of cancer. This article will review some of the common forms of radiation therapy for breast cancer.
When is radiation used to treat breast cancer?
People with breast cancer can be broadly divided into two groups:
- Those with local or regional cancer limited to the breast and area lymph nodes.
- Those with metastatic disease that has spread to other organs (bone, lung, etc.).
If you have local/regional cancer, radiation therapy is often used after surgery to reduce the chance of breast cancer recurrence (cancer coming back). If you need chemotherapy as well, the radiation is typically given after chemotherapy is completed.
The type of surgery that you have determines how your radiation therapy is given. Surgery for breast cancer is most often either a lumpectomy or a mastectomy.
- Lumpectomy (or partial mastectomy) involves removing the part of the breast with the tumor while sparing the remainder of the breast.
- Mastectomy involves the removal of the entire breast tissue on one side, often with the removal of the lymph nodes under the arm (axillary lymph nodes).
Whole Breast Radiation After Lumpectomy
After a lumpectomy, radiation is often given to the entire remaining breast. The exception to this is in some older patients with smaller, less aggressive tumors. This helps to reduce the chance cancer will return in the same location or in other areas of that breast. Radiation is most often given using an external beam technique. This means the radiation beams are angled so that they skim the chest wall but cover the whole breast. This type of radiation is most commonly delivered in daily treatments (5 days a week) over several weeks to the whole breast. An additional week may be used to give an extra dose (called a boost) to the original tumor location.
In some cases after a lumpectomy, radiation will also be given to the lymph nodes under the arm (axillary). This depends on whether or not there was cancer found in the lymph nodes. Ask your radiation oncologist whether you need radiation to the axillary lymph nodes.
Partial Breast Radiation After Lumpectomy
Another common way to give radiation after a lumpectomy is to target only the area of the surgical cavity (the spot where the tumor was removed) with radiation, rather than the whole breast. When breast cancer comes back after treatment, it is often in or near the surgical cavity. By targeting this area, it limits the radiation exposure to the rest of the breast, chest wall, heart, and lung. This method is called "accelerated partial breast irradiation" or APBI. Long-term follow-up effects of this approach are not yet available.
APBI is "accelerated" because you will receive radiation two times a day for a shorter period than traditional external beam radiation. APBI can be delivered using external beam radiation, or through internal radiation (also called brachytherapy). For brachytherapy, a balloon or catheters are placed in the surgical cavity of the breast to deliver radiation right to the cavity. Brachytherapy can even further limit the radiation that hits normal structures like the heart, lung, and chest wall.
Chest Wall and Lymph Node Radiation After Mastectomy
Some patients with breast cancer have a mastectomy. Not everyone who has a mastectomy will need radiation. Radiation is used when there is more of a concern that there are tumor cells still remaining. To determine the level of concern, your provider looks at:
- The tumor size.
- The number of axillary lymph nodes with cancer cells.
- Tumor grade (appearance under the microscope).
- Invasion of lymphovascular spaces within the tumor.
- Surgical margins.
- Your age.
If these things point to a higher risk of cancer coming back at the chest wall (where the breast tissue previously attached) or in the nearby lymph nodes, radiation can reduce that risk. Treatment involves daily radiation (5 days a week) for several weeks, using external beam radiation therapy. In this case, the radiation is designed to skim the chest wall to avoid radiation exposure to the lung and, in left-sided cancers, the heart. If you have had breast reconstruction, the radiation target will include the reconstructed breast.
Special Techniques to Reduce Side Effects
In some cases, it is difficult to avoid the lung and/or heart during radiation. There are some options that can be used to minimize exposure to normal tissues. These options are:
- Treating with a breath-hold position, which increases the distance between the heart and chest wall. This means holding your breath for certain portions of the treatment.
- Giving treatment in the "prone" position (lying on your stomach). This is most often used when treating the left breast, although it can be used for the treatment of both the left and right breast. The prone position is helpful for the treatment of large, pendulous breasts. It allows gravity to pull the breast tissue down and away from the body sparing radiation dose to the heart, lung, and opposite breast.
- Treating with proton radiation, instead of x-ray (photon) radiation. With proton therapy, the radiation can be delivered so that it stops before penetrating the heart and lung tissue.
After treatment, talk with your oncology team about receiving a survivorship care plan, which can help you manage the transition to survivorship and learn about life after cancer. You can create your own survivorship care plan using the OncoLife Survivorship Care Plan. For more information about the long-term effects of radiation therapy for breast cancer, read our article, Survivorship: Late Effects after Radiation for Breast Cancer.