Purpose: To evaluate the ipsilateral breast tumor recurrence (IBTR) after 2 accelerated partial breast irradiation (APBI) techniques (intraoperative electron radiation therapy [IOERT] and external... Show morePurpose: To evaluate the ipsilateral breast tumor recurrence (IBTR) after 2 accelerated partial breast irradiation (APBI) techniques (intraoperative electron radiation therapy [IOERT] and external beam APBI [EB-APBI]) in patients with early-stage breast cancer.Methods and Materials: Between 2011 and 2016, women >= 60 years of age with breast carcinoma or Ductal Carcinoma In Situ (DCIS) of <= 30 mm and cN0 undergoing breast-conserving therapy were included in a 2-armed prospective multicenter cohort study. IOERT (1 x 23.3 Gy prescribed at the 100% isodose line) was applied in 1 hospital and EB-APBI (10 x 3.85 Gy daily) in 2 other hospitals. The primary endpoint was IBTR (all recurrences in the ipsilateral breast irrespective of localization) at 5 years after lumpectomy. A competing risk model was used to estimate the cumulative incidences of IBTR, which were compared using Fine and Gray's test. Secondary endpoints were locoregional recurrence rate, distant recurrence, disease-specific survival and overall survival. Univariate Cox regression models were estimated to identify risk factors for IBTR. Analyses were performed of the intention to treat (ITT) population (IOERT n = 305; EB-APBI n = 295), and sensitivity analyses were done of the per-protocol population (IOERT n = 270; EB-APBI n = 207).Results: The median follow-up was 5.2 years (IOERT) and 5 years (EB-APBI). Cumulative incidence of IBTR in the ITT population at 5 years after lumpectomy was 10.6% (95% confidence interval, 7.0%-14.2%) after IOERT and 3.7% (95% confidence interval, 1.2%-5.9%) after EB-APBI (P =.002). The locoregional recurrence rate was significantly higher after IOERT than EB-APBI (12.1% vs 4.5%, P =.001). There were no differences between groups in other endpoints. Sensitivity analysis showed similar results. Forboth groups, no significant risk factors for IBTR were identified in the ITT population. In the per-protocol population, surgical margin status of the DCIS was the only significant risk factor for developing IBTR in both treatment groups.Conclusions: Ipsilateral breast tumor recurrences and locoregional recurrence rates were unexpectedly high in patients treated with IOERT, and acceptable in patients treated with EB-APBI. (C) 2022 Elsevier Inc. All rights reserved. Show less
Giezen, M.; Kouwenhoven, E.; Scholten, A.N.; Coerkamp, E.G.; Heijenbrok, M.; Jansen, W.P.A.; ... ; Struikmans, H. 2012
PURPOSE: To examine MRI and CT for glandular breast tissue (GBT) volume delineation and to assess interobserver variability. METHODS AND MATERIALS: Fifteen breast cancer patients underwent a... Show morePURPOSE: To examine MRI and CT for glandular breast tissue (GBT) volume delineation and to assess interobserver variability. METHODS AND MATERIALS: Fifteen breast cancer patients underwent a planning CT and MRI, consecutively, in the treatment position. Four observers (two radiation oncologists and two radiologists) delineated the GBT according to the CT and separately to the MR images. Volumes, centers of mass, maximum extensions with standard deviations (SD), and interobserver variability were quantified. Observers viewed delineation differences between MRI and CT and delineation differences among observers. RESULTS: In cranio-lateral and cranio-medial directions, GBT volumes were delineated larger using MRI when compared with those delineated with CT. Center of mass on MRI shifted a mean (SD) 17% (4%) into the cranial direction and a mean 3% (4%) into the dorsal direction when compared with that on the planning CT. Only small variations between observers were noted. The GBT volumes were approximately 4% larger on MRI (mean [SD] ratio MRI to CT GBT volumes, 1.04 [0.06]). Findings were concordant with viewed MRI and CT images and contours. Conformity indices were only slightly different; mean conformity index was 77% (3%) for MRI and 79% (4%) for CT. Delineation differences arising from personal preferences remained recognizable irrespective of the imaging modality used. CONCLUSIONS: Contoured GBT extends substantially further into the cranio-lateral and cranio-medial directions on MRI when compared with CT. Interobserver variability is comparable for both imaging modalities. Observers should be aware of existing personal delineation preferences. Institutions are recommended to review and discuss target volume delineations and to design supplementary guidelines if necessary. Show less
