Breast Conserving Surgery For Breast Cancer:Dosimestric Differences Between Sequential And Simultaneous Integrated Boost

Purpose:Breast conserving surgery followed by whole breast irradiation is widely accepted as standard of care for early breast cancer. Addition of a boost dose to the initial tumor area further reduces local recurrences. The aim of this study was to investigate the dosimetric benefits of the simultaneous integrated boost intensity-modulated radiation therapy (SIB-IMRT) compared to a sequential boost after whole breast irradiation.Methods:Between January 2015 and December 2015 in Guangxi Medical University Affiliated Tumor Hospital,a total of 10 patients who had received left breast-conserving surgery were selected. The median age was 36 years;According to the 7th edition of the AJCC staging criteria,among the patients were 11 cases of stage I,9 cases of stage II;All patients before radiotherapy accepted 6-8 cycles of systemic chemotherapy.Each patient was given two plans by three dimensional treatment planning system:SIB-IMRT plan and Sequential boost after whole breast radiation therapy. Dosimetric comparisons of PTV and OARs between the two plans were performed on each patient by DVH. The data were analyzed statisticallyResults:There is no significant differences in indices(CI、HI). (P≥0.05). Compared to the Sequential boost after whole breast radiation therapy plan,The value of ipsilateral side lung V5、V20、Dmean, the contralateral lung V5 and Dmean, heart V5, V20, V30, and Dmean, contralateral breast dmean, V1 of SIB-IMRT plans are within a limited range, the difference was not statistically significant (P>0.05)Conclusion:Compared to sequential boost after WBI, SIB-IMRT technology to ensure the target area evenly, conformal and make the heart, lung, contralateral breast by irradiation dose and volume in the normal range at the same time, reducing the total treatment time, in theory can be expected to reduce the incidence of radiation injury of oars, so as to further improve the quality of the life of the patients who received breast conserving surgery. SIB-IMRT is a safer option, and can be implemented in clinical practice.