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To identify the risk factors leading to new brain metastases (BM) following brain-directed treatment for initial BM resulting from breast cancer (BC). In this multi-institutional study, 538 BC patients with available follow-up imaging after brain-directed treatment for initial BM were analyzed. Tumor molecular subtypes were classified as follows: hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2−, n = 136), HER2-positive (HER2+, n = 253), or triple-negative BC (TNBC, n = 149). In 37.4% of patients, new BM emerged at a median of 10.5 months after brain-directed treatment for initial BM. The 1-year actuarial rate of new BM for HR+/HER2−, HER2+, and TNBC were 51.9%, 44.0%, and 69.6%, respectively (p = 0.008). Initial whole-brain radiotherapy (WBRT) reduced new BM rates (22.5% reduction at 1 year, p 4) (p

Introduction The purpose of this study was to evaluate the outcomes of upfront surgery followed by radiation therapy (RT) for ipsilateral supraclavicular (SCN) and/or internal mammary (IMN) node-positive breast cancer. Materials and Methods One hundred fifty-eight patients were included; among these, 91 patients were SCN-positive, 54 were IMN-positive, and 13 were SCN- and IMN-positive. Patients underwent breast conserving surgery (n = 74) or mastectomy (n = 84) followed by systemic therapy, and adjuvant RT to whole breast/chest wall with or without regional nodal RT. Regarding regional treatments for SCN and IMN, SCN excision was performed in 59 (37.3%) patients, IMN excision in 10 (6.3%) patients, SCN RT in 143 (90.5%) patients, and IMN RT in 68 (43.0%) patients. Results The median duration of follow-up was 72 months (range, 7-182 months). There were 20 locoregional recurrences and 45 distant metastases. In-field failure was observed only in SCN (n = 8), and 6 of these patients initially underwent SCN excision. The 5-year locoregional recurrence-free survival, disease-free survival (DFS), and overall survival rates were 87.3%, 71.6%, and 89.7%, respectively. Neither SCN excision nor SCN RT dose ≥ 54 Gy improved locoregional control (P = .927 and P = .693, respectively) or DFS (P = .394 and P = .686, respectively). Having ≥ 10 involved axillary lymph nodes was the only independent prognosticator for DFS after adjusting for covariates (P = .003). Conclusion Regional control rate in initially involved SCN and/or IMN was acceptable in patients treated with upfront surgery followed by systemic therapy plus adjuvant RT. More aggressive regional therapy such as SCN excision did not improve locoregional control or survival.

PurposeThe purpose of this study was to investigate the displacement of surgical clips in the excision cavity during whole breast irradiation following breast-conserving surgery (BCS) with or without acellular dermal matrix (ADM) insertion, and to analyze clinicopathologic factors associated with the displacement of surgical clips.Materials and MethodsFrom 2016 to 2017, 100 consecutive breast cancer patients who underwent BCS with the placement of surgical clips (superior, inferior, medial, lateral, and deep sides) in the tumor bed were included in this study. All patients took first planning computed tomography (CT) scan (CT 1) before whole breast irradiation and second CT scan (CT 2) before boost irradiation. Between two sets of planning CT, the displacement of surgical clips was calculated from the ΔX (lateral–medial), ΔY (anterior–posterior), ΔZ (superior–inferior), and three-dimensional (3D) directions. Patients were divided into two groups according to the breast volume replacement with ADM: group A with ADM and group B without ADM.ResultsThe means and 1 standard deviations of 3D displacement for superior, inferior, medial, lateral and deep clips were 5.2±2.9, 5.2±3.2, 5.6±4.5, 5.6±4.3, and 4.9±4.9 mm in entire cohort (n=100); 5.6±2.6, 6.0±3.5, 6.7±5.8, 6.7±5.7, and 6.1±7.4 mm in group A (n=38); 4.9±3.1, 4.8±3.0, 5.0±3.5, 5.0±2.9, and 4.3±2.8 mm in group B (n=62), respectively. The 3D displacements of group A were longer than those of group B, but only significant difference was observed in lateral clip (p=0.047).ConclusionThis study demonstrated displacement of surgical clips during whole breast irradiation in patients with ADM insertion. For patients who had breast volume replacement using ADM, adaptive boost planning should be considered.

PurposeTo evaluate the role of postmastectomy radiation therapy (PMRT) in patients with node-negative breast cancer of 5cm or larger tumors undergoing mastectomyMaterials and MethodsMedical records of 274 patients from 18 institutions treated with mastectomy between January 2000 and December 2016 were retrospectively reviewed. Among these, 202 patients underwent PMRT, while 72 did not. Two hundred and forty-one patients (88.0%) received systemic chemotherapy, and 172 (62.8%) received hormonal therapy. Patients receiving PMRT were younger, more likely to have progesterone receptor-positive tumors, and received adjuvant chemotherapy more frequently compared with those without PMRT (p

Objectives: To evaluate the CT findings of acute radiation pneumonitis (RP) in breast cancer patients undergoing post-operative radiotherapy, and to analyze clinicodosimetric factors associated with acute RP. Methods: Between 2015 and 2017, 61 patients with breast cancer who underwent follow-up chest CT at 3 months after radiotherapy were analyzed. The degree of acute RP on CT was evaluated by the change of extent and scoring system (grade 0, no RP; Grade 1, ground-glass opacities (GGOs); Grade 2, GGOs and/or consolidations; Grade 3, clear focal consolidation; Grade 4, dense consolidation). The dosimetric parameters were calculated from the dose–volume histogram of RT. Results: The acute RP on CT was scored as follows: Grade 0, in 37.7%, Grade 1 in 13.1%, Grade 2 in 44.3%, and Grade 3 in 4.9%. The median extent of RP in patients with Grades 1 to 3 was 6.2 ml (range, 0.2–95.9). There were no clinicodosimetric factors significantly associated with the presence of RP or its severity. One patient developed symptomatic RP. Conclusion: This study showed no correlation between acute RP and clinicodosimetric factors, and acute RP based on CT findings were much more common than symptomatic RP. Advances in knowledge: CT findings of acute RP or extent of RP were not significantly related to clinicodosimetric factors in breast cancer patients.

Background/aim To present the variations in the target delineation and the planning results of intensity-modulated radiation therapy (IMRT) for breast cancers. Patients and methods We requested the target volumes and organs at risk delineation for two cases of left breast cancers, and evaluated the IMRT plans including the supraclavicular and internal mammary node irradiation. Results Twenty-one institutions participated in this study. Differences in the planning target volume among institutions reached up to three-times for breast-conserving surgery (BCS) case and five-times for mastectomy case. Mean heart doses ranged from 3.3 to 24.1 Gy for BCS case and from 5.0 to 26.5 Gy for mastectomy case. Ipsilateral lung volumes receiving more than 20 Gy ranged from 4.7 to 57.4% for BCS case and from 16.4 to 55.5% for mastectomy case. Conclusion There were large variations in the target delineation and planning results of IMRT for breast cancers among institutions. Considering the increased use of breast IMRT, more standardized protocols are needed.

e14008 Background: We analyzed the treatment outcome of breast cancer patients with brain metastases (BM) in Korea to identify the prognostic factors and the role of whole brain radiation therapy (WBRT). Methods: Seven hundred thirty patients of breast cancer with BM treated at 17 institutions in Korea from 2000 to 2014 were analyzed. The median follow-up duration was 12 months. The analysis consisted of three cohorts: in cohort A, a total of 730 patients were included; in cohort B, 538 patients with available follow-up imaging after initial brain-directed treatment; and in cohort C, 54 patients receiving salvage WBRT due to recurrent BM after initial Stereotactic radiosurgery or WBRT. Overall survival (OS) was calculated from BM diagnosis in cohort A or from the last day of salvage WBRT in cohort C. Results: Median OS of cohort A was 15 months. In multivariate analysis, histologic grade 3, extracranial metastasis, number of BM > 4, hormone receptor (HR) or HER2 negativity, and shorter time interval to diagnosis of BM were associated with inferior OS. Among 538 patients in cohort B, 201 showed subsequent development of new BM at a median of 11 months after stereotactic radiosurgery or WBRT for the management of initial BM (at 1 year, HR+/HER2- 51.9%, HER2+ 44.0%, and TNBC 69.6%, respectively; p = 0.008). Upfront WBRT reduced subsequent development of new BM, which showed the significant difference among molecular subtypes (HR+/HER2-, 42% reduction at 1 year, p < 0.001; HER2+, 18.5%, p = 0.004; TNBC, 16.9%, p = 0.071). Multivariate analysis showed that shorter time interval to BM, TNBC subtype, extracranial systemic disease, number of BM > 4, and involvement of both tentoria increased subsequent development of new BM. Anti-HER2 therapy for HER2+ patients and upfront WBRT significantly reduced risk of new BM. In cohort C, upfront WBRT prolonged the salvage WBRT-free duration (median 6.9 vs. 8.7 months, p = 0.058). Median OS was 6.8 months after salvage WBRT. Longer interval to salvage WBRT, controlled primary tumor, high dose of salvage WBRT (BED10 > 37.5 Gy), and systemic treatment after salvage WBRT showed better OS. Uncontrolled extracranial systemic disease and salvage WBRT due to local progression without distant intracranial failure showed worse OS. Conclusions: The rates of new BM showed the significant differences among molecular subtypes. Upfront WBRT decreased subsequent development of new BM and this effect was dependent on the molecular subtype as well. Anti-HER2 therapy for HER2+ patients significantly decreased the subsequent development of new BM. On salvage WBRT setting, the patients having high dose of salvage WBRT, stable extracranial systemic disease and subsequent systemic therapy showed better OS.

Purpose: To evaluate the treatment outcomes of radiotherapy (RT) for breast cancer with ipsilateral supraclavicular (SCL) and/or internal mammary (IMN) lymph node involvement. Methods: A total of 353 patients from 11 institutions were included. One hundred and thirty-six patients had SCL involvement, 148 had IMN involvement, and 69 had both. All patients received neoadjvant systemic therapy followed by breast conserving surgery or mastectomy, and postoperative RT to whole breast/chest wall. As for regional lymph node irradiation, SCL RT was given to 344 patients, and IMN RT to 236 patients. The median RT dose was 50.4 Gy. Results: The median follow-up duration was 61 months (range, 7-173). In-field progression was present in SCL (n=20) and/or IMN (n=7). The 5-year disease-free survival (DFS) and overall survival rates were 57.8% and 75.1%, respectively. On multivariate analysis, both SCL/IMN involvement, number of axillary lymph node ≥4, triple negative subtype, and mastectomy were significant adverse prognosticators for DFS (p = 0.022, 0.001, 0.001, and 0.004, respectively). Regarding the impact of regional nodal irradiation, SCL RT dose ≥54 Gy was not associated with DFS (5-yr rate, 52.9% vs. 50.9%, p = 0.696) in SCL-involved patients, and the receipt of IMN RT was not associated with DFS (5-yr rate, 56.1% vs. 78.1%, p = 0.099) in IMN-involved patients. Conclusion: Neoadjuvant chemotherapy followed by surgery and postoperative RT achieved an acceptable in-field regional control rate in patients with SCL and/or IMN involvement. However, a higher RT dose to SCL or IMN RT was not associated with the improved DFS in these patients. Citation Format: Kim K, Jeong Y, Shin KH, Kim JH, Ahn SD, Kim SS, Suh C-O, Kim YB, Choi DH, Park W, Cha J, Chun M, Lee DS, Lee SY, Kim JH, Park HJ. Impact of regional nodal irradiation for breast cancer patients with supraclavicular and/or internal mammary lymph node involvement: A multicenter, retrospective study (KROG 16-14) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-12-12.

Background For decades, conventionally fractionated whole breast irradiation (CF-WBI) was used after breast conserving surgery (BCS). Pivotal phase 3 trials on hypofractionated-WBI (HF-WBI) showed its non-inferiority as compared to CF-WBI. However, younger patients ( Methods Between 2010 and 2016, a total of 786 patients aged less than 60 years old with early stage breast cancer were treated with postoperative WBI after BCS in three breast cancer centers: 340 underwent HF-WBI while 446 were treated with CF-WBI. Acute toxicity was evaluated at the end of WBI. Late toxicity was evaluated at 6, 12, 24, and 36 months. Results At univariate logistic analysis, hypofractionation showed a significant protective effect in terms of acute edema (p = 0.0001), acute wet desquamation (p = 0.009), chronic edema (p = 0.0001), chronic erythema/pigmentation (p = 0.0001), and breast fibrosis (p = 0.0002). At multivariate logistic analysis, hypofractionation was independent significant factor for acute edema (OR 0.09, 95% CI 0.02 to 0.48; p = 0.005), acute wet desquamation (OR 0.07, 95% CI 0.009 to 0.59; p = 0.014), and chronic edema (OR 0.18, 95% CI 0.04 to 0.75; p = 0.018). Significant association between individual characteristics and toxicity (grade 2 or more) are summarized in Table. Table . 215P Toxicity N Protective factor p-value OR (95%CI) Risk factor p-value OR (95%CI) Acute edema 43 Hypofractionation Dmax/Prescribed dose° 0.0001 0.001 0.09 (0.03-0.30) 0.16 (0.06-0.46) Chemotherapy 0.002 2.63 (1.42-4.90) Chronic edema 50 Hypofractionation Dmax/Prescribed dose° 0.0001 0.003 0.20 (0.09-0.44) 0.31 (0.14-0.66) EIC presence Boost dose >10 Gy Breast size >492 cc 0.0001 0.032 0.003 3.0 (1.66-5.46) 9.02 (1.21-67.45) 2.67 (1.41-5.05) Acute erythema/ pigmentation 163 HER2 positive status Trastuzumab 0.002 0.022 0.30 (0.14-0.63) 0.39 (0.18-0.87) Smoking habits Boost dose >10 Gy Breast size >492 cc 0.001 0.038 0.002 2.14 (1.37-3.32) 2.60 (1.06-6.41) 1.78 (1.24-2.54) Chronic erythema/ pigmentation 110 Hypofractionation Dmax/Prescribed dose° 0.0001 0.001 0.40 (0.25-0.63) 0.45 (0.28-0.73) EIC presence Positive FSM Boost dose >10 Gy Breast size >492 cc 0.0001 0.002 0.007 0.034 2.39 (1.54-3.71) 3.47 (1.56-7.71) 15.43 (2.08-114.3) 1.58 (1.04-2.41) Acute wet desquamation 20 Hypofractionation Dmax/Prescribed dose° 0.009 0.047 0.14 (0.03-0.61) 0.29 (0.08-0.99) - - - Breast fibrosis 117 Hypofractionation Tumor grade Ki67 index Dmax/Prescribed dose° 0.0002 0.022 0.023 0.017 0.44 (0.29-0.68) 0.53 (0.31-0.92) 0.60 (0.38-0.93) 0.58 (0.37-0.91) EIC presence Boost dose >10 Gy Breast size >492 cc 0.0001 0.022 0.0001 3.03 (1.99-4.62) 6.76 (2.04-22.45) 2.84 (1.83-4.41) Conclusions HF-WBI showed significantly improved toxicity outcomes in terms of both acute skin edema and wet desquamation, and chronic skin edema. HF-WBI after BCS should replace CF-WBI independently of age. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure All authors have declared no conflicts of interest.

Background/aim We evaluated dosimetric and clinical results of volumetric-modulated arc therapy (VMAT) treating internal mammary nodes (IMNs) in patients with locally advanced breast cancer. Patients and methods Between July 2012 and December 2013, treatment outcomes of 31 patients with stage III breast cancer treated with postoperative radiotherapy including the IMN field using VMAT were analyzed. Results The median follow-up was 25.2 months. VMAT showed good homogeneity and improved conformity. The incidence of lung toxicity of grade 2 or more was 3.2%, and cardiac toxicity was not observed. No patient developed local recurrence. Conclusion VMAT appears safe for the treatment of locally advanced breast cancer including the IMN field.