Radiation therapy for breast cancer

Radiation therapy for breast cancer uses high-powered X-rays to kill cancer cells. Rapidly growing cells, such as cancer cells, are more susceptible to the effects of radiation therapy than are normal cells.

One of two approaches may be used with radiation therapy for breast cancer:

  • External radiation. External beam radiation, the standard type of radiation therapy, delivers radiation in the form of high-powered energy beams, such as X-rays, to your entire breast from a machine outside your body. This is the most common type of radiation therapy used for breast cancer.
  • Internal radiation. Internal radiation (brachytherapy) involves temporarily placing small radioactive devices in your breast near the tumor site to deliver radiation to affected breast tissue. Internal radiation may be used as an extra radiation boost after external radiation or for small, contained tumors.

Radiation therapy may be used to treat breast cancer at almost every stage. It's an effective way to reduce your risk of breast cancer recurring after surgery. It can also help control the spread of breast cancer and offer pain relief for advanced breast cancer.


Why it's done Risks How you prepare What you can expect Results

Here are the main ways radiation therapy is used to treat breast cancer:

Radiation after lumpectomy

Radiation therapy for breast cancer is almost always recommended after surgery that removes only the tumor (lumpectomy). A lumpectomy alone, without radiation therapy, carries a relatively high risk of cancer recurrence in the affected breast months or years later because of microscopic deposits of cancer left behind after surgery. Radiation helps to destroy remaining cancer cells.

Lumpectomy combined with radiation therapy is often referred to as breast-conservation therapy. In clinical trials comparing lumpectomy with and without radiation therapy, the addition of radiation therapy after a lumpectomy resulted in significantly decreased rates of breast cancer recurrence and proved to be as effective as having the entire breast removed.

Radiation after mastectomy

Removal of the entire breast (mastectomy) usually means you won't need radiation therapy. But radiation therapy is sometimes recommended for women at high risk of cancer recurrence. Factors that may put you at high risk of breast cancer recurrence in your chest wall include:

  • Lymph nodes with signs of breast cancer. Underarm (axillary) lymph nodes that test positive for cancer cells are an indication that some cancer cells have spread from the primary tumor. The more positive nodes you have, the more likely your doctor is to recommend radiation therapy. Experts agree that having four or more positive nodes is a clear indication for radiation therapy after mastectomy, although data suggest that even women with fewer positive lymph nodes may benefit from radiation therapy.
  • Large tumor size. A tumor greater than 5 centimeters (about 2 inches) generally carries a higher risk of recurrence than do smaller tumors.
  • Tissue margins with signs of breast cancer. After breast tissue is removed, the margins of the tissue are examined for signs of cancer cells. Very narrow margins or margins that test positive for cancer cells are a risk factor for recurrence.

Radiation for locally advanced breast cancer

Radiation therapy can also be used to treat:

  • Breast tumors that cannot be surgically removed.
  • Inflammatory breast cancer, an aggressive type of breast cancer that spreads to the lymph channels of the skin covering the breast. People who have this type of breast cancer typically receive chemotherapy before a mastectomy, followed by radiation, to decrease the chance of recurrence.

Radiation for managing metastatic complications

If breast cancer has spread to other parts of your body (metastasized) and a tumor is causing pain or some other symptom, radiation can be used to shrink the tumor and ease that symptom.

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