Breast conservation has been shown to be a safe modality of treating early stage breast cancer as long as radiation is used after surgery. The initial trials utilized whole breast radiation 5 days a week for 6 weeks. Accelerated partial breast radiation (APBI), or brachytherapy, has now been shown to also be an effective way to give the radiation therapy safely.
The main difference with brachytherapy is that the radiation source is placed at the site of the lumpectomy scar. Using this, an accelerated or higher dose of radiation is directed right to the tumor bed, minimizing damage to normal breast tissue and skin. A device through which radiation is delivered is placed into the breast after the breast cancer has been removed. When brachytherapy was first developed, multiple tubes were placed into the breast to deliver the radiation. This has been replaced by a single device placed into the breast.
The Mammosite catheter was the first device tested in a clinical trial in America. It essentially resembled a balloon surrounding a catheter. The balloon kept the breast tissue away from the catheter so the physicist and radiation oncologist could plan the dose of radiation to be delivered. Since there is one catheter, the dose of radiation is delivered in an even 1cm about the edge of the balloon, delivering the dose of radiation 1 cm past the surgical margin.
Once the safety of this type of therapy was established, newer delivery modalities were developed. These included the SAVI, Contura, and Best Double-Balloon Breast Brachytherapy Applicator. In each of these devices there are multiple catheters that will allow conformation, or specific shaping, of a radiation dose around the catheters.
The SAVI device has 6-8 catheters which open in a manner similar to an egg beater. This allows direct delivery of the dose at the specific margins. It also allows the radiation treatment to be directed towards the area of concerns and away from the skin, heart and lung.
The Contura device also uses multiple catheters, which are more tightly grouped and situated in the central portion of a balloon.
The Best Double-Balloon Breast Brachytherapy Applicator has an outer balloon and an inner balloon which separate the multiple inner catheters to facilitate dose distribution and conformity.
Typical patients who are candidates for brachytherapy have:
- Cancers less than 3 cm in size
- No cancer in their sentinel lymph nodes
- Not had chemotherapy prior to their breast cancer surgery
Your radiation oncologist will decide if brachytherapy is an option for you.