Updated September 03, 2013.
Written or reviewed by a board-certified physician. See About.com's Medical Review Board.
For small, early-stage breast cancers that don't qualify for brachytherapy, whole breast radiation may be overkill, but external beam accelerated partial breast irradiation (EB-PBI) may be the perfect fit. Partial breast radiation targets only the small part of your breast where the tumor was removed during a lumpectomy. There are several different approaches to EB-PBI that give you safe and effective treatment in only one to five days.
Targeting the Tumor From The Outside:
Accelerated partial breast radiation can be done from outside the body with external radiation beams or from within the breast using brachytherapy techniques. EB-PBI is done from outside the body and delivers cancer-fighting energy to a targeted area of tissue, sparing healthy tissue and nearby organs.
Advantages of External Beam Partial Breast Radiation:
Whole Breast Radiation (WBI) has been used for a long time, and it is effective at preventing breast cancer recurrence. But WBI may affect your heart, ribs, lungs, breast tissue, chest muscles, lymph nodes and skin. EB-PBI may still affect the ribs and lung nearest the breast in treatment, but your body receives lower doses of radiation than WBI delivers. Partial breast radiation results in efficient, targeted treatment and is effective in preventing breast cancer recurrence.
Treatment Planning for EB-PBI:
Your breast and your lumpectomy cavity are three-dimensional, so special imaging techniques must be used to locate, map, and plan your partial breast radiation.
 You may have a variety of imaging studies done before treatment –- ultrasound, CT scan, and CT scan treatment simulation. You may be asked to lie on your back or on your stomach for the scans as well as the treatment.
Conformal X-Ray Therapy:
This type of EB-PBI uses X-ray energy, just like whole breast radiation, but shapes the beam of energy to your tumor area only. Research is being done with proton and neutron beam energy, other forms of ionizing radiation. Here are two methods of conformal X-ray therapy:
- 3D Conformal: Targeted external beams shaped to fit your tumor area
- Intensity Modulated Radiation Therapy (IMRT): Also called TomoTherapyTM, this treats the tumor area one small part at a time, from various angles. See a video about IMRT.
Special Methods of Partial Breast Radiation:
- Image Guided Radiation Therapy (IGRT): Contoured radiation for boost dose after WBI to give you more protection against recurrence.
- Intraoperative Radiation Therapy (IORT): One treatment only, given in the operating room during your lumpectomy. This may use X-ray energy or a brachytherapy device.
Sources:
Bush DA, Slater JD, Garberoglio C, Yuh G, Hocko JM, Slater JM. A technique of partial breast irradiation utilizing proton beam radiotherapy: comparison with conformal x-ray therapy. Cancer J. 2007 Mar-Apr;13(2):114-8.
Anudh K. Jain, Laura A. Vallow, Ashley A. Gale, Steven J. Buskirk. Does Three-Dimensional External Beam Partial Breast Irradiation Spare Lung Tissue Compared With Standard Whole Breast Irradiation? International Journal of Radiation Oncology * Biology * Physics - 1 September 2009 (Vol. 75, Issue 1, Pages 82-88, DOI: 10.1016/j.ijrobp.2008.10.041)
Elizabeth M. Murray, I. Dudley Werner, et. al. Neutron Versus Photon Radiotherapy for Local Control in Inoperable Breast Cancer. Strahlentherapie und Onkologie, Volume 181, Number 2 / February, 2005.
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