Breast Cancer Radiation Therapy

Radiation treatment is an important tool in treating breast cancer. The radiation oncologists at Mount Sinai Health System deliver high-quality care, based on a treatment plan personalized for your needs. We are actively engaged in research to improve cancer therapy. Our physicians, nurses, physicists, radiation therapists, and support staff work as a team to give you the most compassionate and advanced cancer care available. We strive to make treatment as physically and emotionally comfortable as possible. Using the latest techniques, we can pinpoint your cancer while protecting normal cells.

Generally, patients receive radiation therapy after part of the breast is removed, in a procedure called a lumpectomy or breast-conserving surgery. The radiation is used to get rid of any cancer cells that may be left in the body. This helps prevent cancer from coming back. Radiation treatment following a lumpectomy typically lasts for three to four weeks.

We may also use radiation therapy after removing the entire breast (mastectomy). Generally, we use this approach if you have cancer in the lymph nodes or the tissue around a tumor. In this case, we direct the radiation at the reconstructed breast or the chest wall and the area where the lymph nodes had been. Postmastectomy radiation therapy typically takes five weeks.

External Beam Radiation Treatment

Most of the time, we use external beam radiation treatment (EBRT). We deliver this treatment to the whole breast using a machine called a linear accelerator. You receive EBRT daily, Monday to Friday. In some women, we also provide a “boost” dose of radiation. This entails several more radiation treatments to the surgical site. It further reduces the chance of a cancer recurrence.

Doctors deliver external beam radiation treatment in several ways. Your radiation oncologist will determine the best approach for you. We strive to deliver radiation as precisely and as safely as possible. The types of EBRT include:

  • 3-D conformal radiation treatment
  • Intensity-modulated radiation treatment
  • Proton beam therapy: This is a newer, advanced type of external beam radiation therapy. It uses proton beams rather thanphoton beams. It allows us to be even more precise and provide even greater protection for nearby normal tissues. It is beneficial in certain cases and your doctor will discuss it with you, if appropriate.

We use one of two positions for providing radiation treatment. We select the approach that allows us to target the cancer cells while avoiding your heart and lungs. A computerized tomography scan will help us determine the best position for you. During treatment, you will either lie:

  • On your back, which is often used after mastectomy, to better target your lymph nodes
  • On your chest

If you have cancer on your left side and are lying on your back, we may have you hold your breath during treatment. This keeps your heart away from your left breast, minimizing radiation to the heart and lungs.

Some patients may receive partial-breast radiation treatment instead of whole-breast radiation. This means we target only where the tumor was removed, with a margin of breast tissue around it. We typically use this approach for certain postmenopausal women who had small, estrogen receptor-positive tumors. Your radiation oncologist will discuss this with you if it is appropriate.

Intra-operative Radiation Treatment

At The Mount Sinai Hospital, we also offer intra-operative radiation treatment (IORT). This is a relatively newer technique. It is most appropriate for select patients with small, estrogen receptor-positive breast cancers and no evidence of cancer in the lymph nodes. We use this approach at the time of lumpectomy, right after we remove the tumor. We deliver IORT using a tiny radiation device that we insert into the lumpectomy incision. Then we can direct radiation treatment precisely where you need it most: where the cancer was removed. This is the spot where the cancer is most likely to come back.

IORT is a 20- to 40-minute treatment during surgery. You will still be under anesthesia. This approach minimizes radiation exposure to healthy tissues and organs nearby. It is not effective for everyone. If you have no high-risk features according to your final pathology report after surgery, IORT is considered effective. You will not need any more radiation treatment. If you do show high-risk features, we may use IORT to “boost” treatment. You will still need three more weeks of external radiation treatment.

Working with Your Radiation Oncologist

You will meet with your radiation oncologist either before or after surgery. Our expert will explain your personalized radiation treatment plan. Our whole radiation oncology team will work closely with you and the rest of your medical team to give you the best possible result.