APBI:
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.

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 is effective and safe with a proven track record, but it makes you wonder "is all this necessary for a little tumor?". The photo on the right shows standard radiation therapy, which enters the body via two beams, and all the area in red is treated to a high dose.

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. At our clinic, we have been using brachytherapy for breast cancer since 1997, and have a long experience.

External Beam APBI

We use tomotherapy in 10 treatments over 5 days. This is a nice treatment which can be valuable when someone is not a good candidate for brachytherapy or doesn't want to have that procedure. Brachytherapy is usually more targeted than external beam radiation for APBI. .

Brachytherapy APBI

There are two common methods for doing 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 which 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, and perhaps not as reproducible between different cancer centers.

The Mammosite device uses a single thicker catheter which enters into a cavity inside the breast where the tumor used to be. A ballon is then inflated to a diameter of about 2 inches, which entirely fills the cavity. This procedure is more reproducible between different cancer centers. Not everyone can have the mammosite however -- it should be done within 6 weeks of surgery and there should be a cavity (seroma) still present in the breast whish 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. Here are a list of criteria for APBI.

Results

APBI is a new concept, and there are good 5 - 10 year results available for multicatheter brachytherapy APBI. Not all doctors believe in it. There is a large ongoing multihospital randomized study underway (RTOG 0413) to try to answer the question of whether APBI is an acceptable option to regular whole breast external beam radiation. Certainly, selecting the right women for this treatment and doing a good treatment technique are vital to having good results.

For mammosite, a William Beaumont Hosp study showed a 3% rate of cancer recurrence in the breast within the first 3 years. This would be similiar to what is seen after external beam radiation to the whole breast. Cosmetic appearance was good/excellent in 88% at the 3 year mark.

A study from Hungary in 2007 randomly compared women to receive either 1)APBI with multicatheter brachytherapy, 2)APBI with electron external beam radiation, or 3)standard whole breast radiation. There was no statistical difference in the 5 year rate of cancer recurrence in the breast, which was 3.4 - 4.7%. The brachytherapy patients had the best cosmetic appearance of the breast afterwards.