When comparing simplified geometric figures, IOERT delivers the most homogeneous dose distributions. However, in clinical reality PTVs often present asymmetric shapes instead of ideal geometries. Due to a strictly centric dose fall-off, any system with a round central applicator will have technical limits. During IOERT margin-directed applicator guidance is possible and interstitial brachytherapy allows for polygonal dose shaping. These techniques seem to be superior for asymmetric PTV irradiation.
Aim of this study is to show that ipsilateral breast tumor recurrence (IBTR) after breast conserving surgery can be reduced by proper surgery and modern radiotherapy techniques. Three hundred and seventy eight women with stage I or II breast cancer had breast conserving surgery and received 51-56.1 Gy of postoperative radiation to the whole breast in 1.7 Gy fractions, but patients received different boost strategies. Group 1 (n 5 188) received electron boost radiation of 12 Gy subsequent to the irradiation to the whole breast, group 2 (n 5 190) received intraoperative electron boost radiation of 9 Gy directly to the tumor bed, followed by whole breast irradiation. After a median follow up period of 81.0 months in group 1 and a median follow up period of 51.1 months in group 2, 12 IBTRs (6.4%) could be observed in group 1 and no IBTR could be observed in group 2 (0.0%). The 5-year actuarial rates of IBTR were 4.3% (95% CI, 1.9-8.3%) and 0.0% (95% CI, 0.0-1.9%), respectively (p 5 0.0018). The 5-year actuarial rates of distant recurrence were 8.6% (95% CI, 4.9-13.5%) and 4.2% (95% CI, 1.8-8.2%), respectively (p 5 0.08). The 5 year disease-free survival rates were 90.9% (95% CI, 85.8-94.7%) in group 1 and 95.8% (95% CI, 91.8-98.2%) in group 2 (p 5 0.064). Immediate IORT-boost and whole breast irradiation yields excellent local control at 5 years, and was associated with a statistically significant decreased rate of IBTR compared with a similar cohort of patients treated with whole breast irradiation and conventional electron boost. ' 2005 Wiley-Liss, Inc.
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