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Accelerated Partial Breast Irradiation for Early-stage, Low-risk Breast Cancer

US Oncology Review, 2005;1(1):1-3 DOI: http://doi.org/10.17925/OHR.2005.00.00.1j

Abstract:

Reference Section a report by Phillip M Devlin, MD Director, Brachytherapy and Fellowship Program, Department of Radiation Oncology, Brigham & Women's Hospital and Dana-Farber Cancer Institute Breast-conserving therapy (BCT; tumor excision with adequate margins with axillary nodes dissection followed by external beam radiation therapy (EBRT)) has become the standard of care treatment for women with stage I/II breast cancer.The overall goal of radiation therapy is to eliminate microscopic foci of cancer remaining after surgery. Standard therapy after lumpectomy is six to seven weeks of EBRT to the whole breast.Unfortunately,fewer than 50% of American women choose BCT over mastectomy, even though there is more than 20 years' excellent scientific data showing that breast conservation is equivalent to mastectomy for disease control and survival, with much better cosmetic and psychologic outcomes.

The reason that so few women choose BCT is largely due to the inconvenience of attending six to seven weeks of daily radiation treatments (RT). Often women, especially in the heartland of America, are many hours away from the nearest radiation facility, and many do not have the ability to take time away from employment or family commitments to attend such therapy. Many employers simply cannot afford extended time away for protracted therapy as a healthcare benefit. Reducing time from six or seven weeks to four or five days can change this pattern.Accelerated partial breast irradiation (APBI) delivery of RT to the tumor bed in four to five days allows not only for shortening of treatment time but also limits the dose to non-involved normal tissues such as the skin, heart, lungs and chest wall, and potentially reduces both the acute and chronic toxicity of RT, which would lead to improved quality of life for patients. Also, APBI may eliminate scheduling problems regarding systemic chemotherapy when indicated.The goals of this article are to review APBI techniques and discuss indications, follow-up results, and future research for this therapy.

There are two types of APBI: EBRT (intraoperative electron beam radiation therapy and intensity modulated radiation therapy) and brachytherapy (BT; interstitial and intracavitary). In EBRT, APBI source of radiation is external to the patient, while in BT it is placed inside or near the tumor.All these techniques will be studied and compared with each other and standard whole breast irradiation in an upcoming National Surgical Adjuvant Breast and Bowel Project (NSAPB) Radiation Therapy Oncology Group (RTOG) study. All APBI techniques allow definition of the highest risk area of the breast and delivery of highly focused radiation to this smaller, more precise area of the breast.The advantage of APBI is greater specificity of the delivered dose, which allows for optimizing the cosmetic appearance of the breast and avoids potentially painful fibrosis and necrosis. The scientific rationale for APBI is based on the finding that the vast majority of recurrences after lumpectomy occur in the tumor bed region, with only 1% to 6% incidence of remote (far away or elsewhere in the breast) failures, therefore whole breast radiation therapy may not be needed in appropriately selected patients. However, as the breast is attached to the chest wall, the target area in the breast can be subject to motion related to respiration.This can have the unwanted side effect of making it necessary to identify an even larger area before treatment, and therefore losing some of the advantage of these APBI over the standard whole breast radiation.