الفهرس 
Breast cancer EpidemiologyOnly 14 pages are availabe for public view
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Abstract
The combination of breast-conserving surgery and radiotherapy, known as “breast-conserving therapy” (BCT), is a widely accepted treatment option for most women with clinical Stage I or II invasive breast cancer.
Traditionally, patients undergoing BCT have received whole-breast irradiation (WBI), consists of 4 to 5 weeks of WBI for a total dose of 45 to 50 Gy in 23 to 25 fractions, usually followed by a boost of 10 to 16 Gy in 5 to 8 fractions to the tumor bed.
Women who choose BCT, therefore, commit to 6 to 7 weeks of daily radiation visits to complete local management of their breast cancer.
APBI allows for shorter treatment schemes than does WBI (typically 1 week), and normal-tissue toxicity should be reduced by the decrease of the treatment volumes (i.e., cardiac damage and radiation pneumonitis). However, APBI will only emerge as a viable treatment option if it confers the same local control benefits as does WBI.
Other potential benefits of APBI include patient convenience with reduction in the length of the RT course, easier integration with chemotherapy, and reduction in the overall treatment cost.
A number of studies of APBI have been performed in North America and Europe in which Clinical results are promising, although with relatively short follow-up.
These results demonstrate that 3D-CRT is a promising method for delivering PBI, technically feasible and with minimal acute toxicity to date. Additional follow-up will be needed to assess the long- term effects of these larger fraction sizes on normal tissue sequelae and overall treatment efficacy and also to assess how to overcome the technical difficulties to this procedure
However, the use of 3D-CRT to deliver PBI has also several potential disadvantages:
First, because the breast is not a stationary target, potentially larger volumes of normal breast tissue may need to be irradiated to avoid a geographic miss, with uncertain effects on cosmetic outcome.
Second, extreme care must be taken by the surgeon to accurately delineate the lumpectomy, because the RT margin will be entirely dependent upon their efforts.
Third, it is not clear whether the fractionation schedules used with interstitial brachytherapy that have provided excellent local control rates and good/excellent long-term cosmetic results can be extrapolated (radio-biologically) to external beam radiotherapy.
Fourth, it is still prematurely to put solid criteria about who is truly candidate to receive APBI.
Fifth, one of the limitations of the current technique relates to the additional margins that need to be added to the CTV to account for breathing motion and treating setup uncertainties.
Because of these large margins, it was necessary to develop technical parameters to help identify unsuitable patients before dosimetric treatment planning. Theoretically, better positioning and immobilization or real-time image guidance could be used to reduce these margins and increase the percentage of patients treatable with 3D-CRT. Both of these concepts are currently being investigated to potentially help alleviate this problem.
Utilizing 3D-CRT to deliver PBI is technically feasible, and acute toxicity to date has been minimal. Additional follow-up will be needed to assess the long-term effects of these larger fraction sizes on normal-tissue sequelae and the impact of this fractionation schedule on treatment efficacy.