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Accelerated Partial Breast Irradiation (APBI) Utilizing HDR Brachytherapy
Breast cancer is the most common cancer in women besides skin cancer. Breast cancer accounted for 27% of all new cancer cases in women in the U.S. in 2010 and was the second leading cause of cancer deaths after lung cancer. Vigilant screening programs have resulted in breast cancer being diagnosed at an earlier stage. For patients diagnosed with early-stage breast cancer, removal of part of the breast (lumpectomy) followed by radiation therapy (to the breast results in the same cure rates as surgical removal of the whole breast (modified radical mastectomy).
Breast conservation therapy (BCT) involved undergoing a lumpectomy, lymph node sampling and subsequent radiotherapy. The traditional way of delivering radiotherapy has been with daily external treatments over a period of 6-7 weeks. Accelerated partial breast irradiation (APBI) is a relatively new form of radiation treatment for early-stage cancer. APBI involves the temporary placement of a radioactive source inside of the lumpectomy cavity. Only breast tissue within 1.0 cm (0.4 inch) of the lumpectomy cavity is treated with APBI, not the whole breast. A surgeon places an APBI catheter inside of the lumpectomy cavity in his or her office one to three weeks after performing a lumpectomy and sentinel lymph node biopsy. A radioactive source is subsequently passed through a catheter twice each day for a total of 10 outpatient treatments over 5-7 days. Each radiation treatment takes only 15 minutes. No radiation is left behind in the patient.
One advantage of APBI over whole breast irradiation is that the radiotherapy is delivered over only one week rather than 5-7 weeks. Another advantage of APBI is that the volumes of heart and lung irradiated to clinically significant levels are lower than with whole breast irradiation. In addition, the appearance of the breast after APBI compares favorably with the appearance after whole breast irradiation.
Patients may be considered for APBI outside the setting of a clinical study if they are 50 years of age or older and their breast cancer is less than or equal to 3.0 cm (1.2 inches) and is estrogen and progesterone receptor positive. In addition, none of the lymph nodes in the armpit, known as the axillary nodes, should be involved.
The Advantages to APBI with HDR brachytherapy:
- Treatment can be completed in up to 5 days.
- High doses of radiation are delivered to the lumpectomy cavity where cancer is most likely to recur and limits the amount of surrounding normal tissues exposed to radiation, potentially minimizing side effects and improving cosmesis.
- Treatment is delivered on an outpatient basis without the need for hospitalization.
- Cosmesis is good to excellent in more than 88% of patients at two years after treatment.
Breast brachytherapy as the sole method of radiation therapy after breast conserving surgery offers improved convenience, quality of life, and in breast control rates of 95%.
Accelerated Partial Breast Irradiation (APBI) is part of a multidisciplinary approach to breast conservation therapy. The MammoSite Radiation Therapy System (RTS) is a widely used method of APBI and relatively new and innovative technique of delivering radiation from inside the breast directly to tissue where cancer is most likely to recur.
There are numerous devices used for APBI which include the Mammosite®, Contura®, and SAVI® brachytherapy catheters.
CONTURA®
The Contura ® is a smaill balloon-based device implanted into the breast to treat the tissue surrounding the cavity after lumptectomy surgery. Advantages of the Contura®multi-lumen balloon (MLB) catheter are that one can: 1) suction out air/blood from the lumpectomy cavity to allow for APBI in challenging cases, 2) contour the radiation so as to avoid a radiation hot spot in the skin or ribs. Previous balloon brachytherapy used a single channel to place the radiation seed. The Contura® MLB uses five separate “lumens” or channels inside the balloon to place the radiation. The additional channels help the physician to shape or "contour" the radiation dose away from the skin or chest wall. It also employs a vacuum to help the balloon fit closely within the often irregularly shaped lumpectomy cavity, so the targeted areas receive the prescribed therapeutic dose.
For more information about the Contura® MLB please select the hyperlink below
http://senorx.com/products/apbi/index.asp
MAMMOSITE®
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Courtesy of Hologic Corporation
and affiliates
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The Mammosite® balloon catheter is a small balloon device which is implanted into the lumpectomy cavity to deliver radiation therapy. The original catheter utilized a single channel to deliver the radiation treatments. Much of the data supporting the use of APBI using HDR brachytherapy was based on the results of the mammosite balloon catheter. The mammosite balloon catheter has since been improved and now utilizes 4 channels which can be used to help “sculpt” the dose of radiation to the lumpectomy cavity.
For a demonstration of the mammosite® balloon catheter, please select the hyperlink below.
http://www.mammosite.com/breast-lumpectomy/how-it-works.cfm
SAVI®
The SAVI® (Strut-Adjusted Volume Implant) differs from the Mammosite® and the Contura® in that it is not a “balloon” type device. The SAVI® device utilizes numerous flexible catheters which can be expanded in the breast cavity. Once it is in the treatment configuration, it resembles an egg beater. The SAVI® and utilizes more catheters than the Mammosite® or the Contura® and as a result, the physician has greater control over the radiation dose so as to avoid a radiation hot spot in the skin or ribs.
For more information about the SAVI® please select the hyperlink below
http://www.ciannamedical.com/for_women/savi_anim.htm
http://www.ciannamedical.com/for_women/understanding_treatment.htm
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