Radiation therapy is a procedure that kills cancer cells with high-energy rays (or particles). In addition to other therapies, certain people with Breast Cancer may require radiation. For some cases, the radiation treatment is used:

• After breast-conserving Surgery (BCS), help to reduce the risk of cancer returning to the same or surrounding lymph nodes.
• After mastectomy, particularly if the cancer is larger than 5 cm (about 2 inches), if there is cancer in several lymph nodes, or if other surgical margins have cancer such as the skin or muscle.
• If cancer has spread to other areas of the body, for example the bones or brain.

External beam Radiation therapy (EBRT) and brachytherapy are the primary forms of Radiation therapy that can be used to treat Breast Cancer.

Types and schedules of external beam radiation for breast cancer

Whole breast radiation

• The standard schedule for getting whole breast radiation is 5 days a week (Monday through Friday) for about 6 to 7 weeks.
• Another option is hypofractionated radiation therapy where the radiation is also given to the whole breast, but in larger daily doses (Monday through Friday) using fewer treatments (typically for only 3 to 4 weeks). In women treated with breast-conserving Surgery (BCS) and without cancer spread to underarm lymph nodes, this schedule has been shown to be just as good at keeping the cancer from coming back in the same breast as giving the radiation over longer periods of time. It might also lead to fewer short-term side effects.

Accelerated partial breast irradiation

In select women, some doctors are using accelerated partial breast irradiation (APBI) to give larger doses over a shorter time to only one part of the breast compared to the entire breast. Since more research is needed to know if these newer methods will have the same long-term results as standard radiation, not all doctors use them. There are several different types of accelerated partial breast irradiation:

• Intraoperative Radiation therapy (IORT): In this approach, a single large dose of radiation is given to the area where the tumour was removed (tumour bed) in the operating room right after BCS (before the breast incision is closed). IORT requires special equipment and is not widely available.

• 3D-conformal Radiation therapy (3D-CRT): In this technique, the radiation is given with special machines so that it is better aimed at the tumour bed. This spares more of the healthy breast. Treatments are given twice a day for 5 days.
• Intensity-modulated Radiation therapy (IMRT): IMRT is like 3D-CRT, but it also changes the strength of some of the beams in certain areas. This gets stronger doses to certain parts of the tumour bed and helps lessen damage to nearby normal body tissues.
• Brachytherapy: See brachytherapy below.

Women who are interested in these approaches may want to ask their doctor about taking part in clinical trials of accelerated partial breast irradiation.

Chest wall radiation

If you had a mastectomy and none of the lymph nodes had cancer, radiation will be given to the entire chest wall, the mastectomy scar, and the areas of any surgical drains. It is typically given daily 5 days a week for 6 weeks.

Lymph node radiation

Whether or not you have had BCS or a mastectomy, if cancer was found in the lymph nodes under the arm (axillary lymph nodes), this area may be given radiation. In certain cases, the lymph nodes above the collarbone (supraclavicular lymph nodes) and behind the breast bone in the centre of the chest (internal mammary lymph nodes) will also receive radiation along with the underarm nodes. It is typically given daily 5 days a week for 6 weeks at the same time as the radiation to the breast or chest wall is given.

Possible side effects of external radiation

The main short-term side effects of external beam Radiation therapy to the breast are:

• Swelling in the breast
• Skin changes in the treated area similar to a sunburn (redness, skin peeling, darkening of the skin)
• Fatigue

Your health care team may advise you to avoid exposing the treated skin to the sun because it could make the skin changes worse. Most skin changes get better within a few months. Changes to the breast tissue usually go away in 6 to 12 months, but it can take longer.

External beam Radiation therapy can also cause side effects later on:

• Some women may find that Radiation therapy causes the breast to become smaller and firmer.
• Radiation may affect your options for breast reconstruction later on. It can also raise the risk of problems with appearance and healing if it’s given after reconstruction, especially
• Women who have had breast radiation may have problems breastfeeding.
• Radiation to the breast can sometimes damage some of the nerves to the arm. This is called brachial plexopathy and can lead to numbness, pain, and weakness in the shoulder, arm, and hand.
• Radiation to the underarm lymph nodes might cause lymphedema, a type of Pain and swelling in the arm or chest.
• In rare cases, Radiation therapy may weaken the ribs, which could lead to a fracture.
• In the past, parts of the lungs and heart were more likely to get some radiation, which could lead to long-term damage of these organs in some women. Modern Radiation therapy equipment better focuses the radiation beams, so these problems are rare today.
• A very rare complication of radiation to the breast is the development of another cancer called an angiosarcoma.