Accelerated partial breast irradiation (APBI) is an important development in breast cancer treatment. Otherwise known as intracavity brachytherapy, It involves placing a small, deflated balloon attached to a thin tube into the space left by the lumpectomy. The balloon is then filled with saline and left in place throughout the treatment. A radioactive source (seed) is threaded into the balloon through the tube for a short time period during each treatment and then removed. An advanced computer system accurately controls seed placement to make sure only the tissue closest to the balloon is affected by radiation. Treatments are delivered twice a day for five days, at which time the balloon is deflated and removed. One leading APBI brachytherapy system, the SenoRx Contura™ Multi-Lumen Balloon , uses vacuum ports to remove excess fluid and air which allows close adherence within the lumpectomy cavity. This adherence provides for more uniform treatment of the surrounding tissue. The Contura MLB also contains five separate lumens (tubes) inside the balloon that enable the doctor to shape the radiation dose toward the desired target area and away from the skin or chest wall. This ability to shape the dose allows doctors to treat more patients as they are not limited in the size or shape of the breast with relation to skin or chest wall distance.

After a lumpectomy, 6-to-7 weeks of external beam, whole-breast radiation therapy has been the standard of care. APBI changes this therapy approach in two major ways. For one thing, it shortens the treatment time from six weeks to just 5 days. Secondly, it reduces the treatment area from the entire breast to only the tissue surrounding the lumpectomy cavity. This is where most cancers are likely to recur. The goal is to use a less invasive and more focused treatment without compromising results. In clinical trials APBI has been shown to be as effective as whole breast irradiation.