Radiation Therapy for Breast Cancer
Radiation therapy is almost always recommended after a lumpectomy for breast cancer. Typically it takes 6 to 7 weeks, and treats the entire breast along with some underlying ribs, muscles, a crescent of lung, sometimes a bit of heart, and all the skin on the breast. It has a proven track record, but it makes you wonder if it is all necessary for a little tumor.
APBI: Accelerated Partial Breast Irradiation
Accelerated Partial Breast Irradiation (APBI) is a new way to give radiation therapy to the breast after a lumpectomy, a way that is much faster and treats less of the breast and less of the body.
APBI does not treat the entire breast. It focuses on the part of the breast where the tumor was removed. This allows a smaller region to be radiated, which in turn results in less radiation to the lung, heart, ribs, muscles, and skin. It also allows the treatment to be given in a more condensed, faster schedule.
APBI can be given with either brachytherapy (radioactive sources in the breast) or with external radiation beam techniques. CTCA has been using brachytherapy for breast cancer since 1997.
External Beam APBI
Tomotherapy is typically given in 10 treatments over 5 days. This may be a good treatment option for a patient who is not a good candidate for brachytherapy, or who doesn't want to have that procedure. Although brachytherapy is usually more targeted than external beam radiation for APBI.
There are two common methods for breast brachytherapy: 1) placing multiple catheters into the breast which surround the area where the tumor used to be, or 2) placing a single catheter in the breast which contains a balloon that inflates once inside the breast (Mammosite™). A radioactive pellet is inserted into the catheter(s) twice daily for 5 days via an HDR afterloading machine, then the catheters are removed.
Multicatheter brachytherapy involves placing several catheters into the breast, usually 10 - 20, although the number may vary. This is the longest researched method of APBI in the US. It offers great flexibility and is potentially the most targeted APBI treatment. It is also the most technical to perform.
The Mammosite device uses a single thicker catheter which enters into a cavity inside the breast where the tumor used to be. A balloon is then inflated to a diameter of about 2 inches, which entirely fills the cavity.
The Mammosite may not be appropriate for all patients. It should be done within six weeks of surgery and there should be a cavity (seroma) still present in the breast which is not too big, not too small, and not too close to the skin surface.
Who Can Have APBI?
Women with small early breast cancers are typically eligible for APBI. There is still uncertainty about who it is best for, and when there is doubt your doctor may recommend standard radiation methods. Generally you need a small tumor, with clear surgical margins after lumpectomy, and preferably no lymph nodes containing cancer.