ESTRO 38 Abstract book

S708 ESTRO 38

(National Taiwan University Hospital cohort) who were treated with breast-conserving surgery (BCS) for ductal carcinoma in situ (DCIS). This study aimed to whether aforementioned prognostic factors predicted lower IBTR in breast DCIS patients from the other 12 hospitals of Taiwan (Taiwan cohort) who underwent BCS alone. Material and Methods Data for 910 women with breast DCIS who underwent BCS at Taiwan cohort between January 2004 and December 2011 were analyzed. The patients were divided into different categories according to the recurrence risk predicted using the USC/VNPI score (4-6, 7-9, and 10-12), ECOG E5194 criteria (cohort 1, and non- cohort 1). The IBTR (included DCIS and invasive cancer of the ipsilateral breast area) was calculated by the Kaplan-Meier method. The prognostic effects of age, estrogen receptor status, USC/VNPI score, ECOG E5194 cohort 1 criteria, and tamoxifen use were evaluated by log-rank tests. Results Of the patients, 549 were treated with breast irradiation after BCS and 361 were not. The patients who were treated with radiotherapy (RT) tended to have higher USC/VNPI scores (7-11) (p < 0.001), and to have a trend to meet the ECOG E5194 non-cohort 1 criteria (p = 0.091). With a median follow-up of 6.3 years (95% confidence interval 6.1 to 6.5), the 7-year risk of IBTR rate was 3.4% (n = 16) in the patients who received RT and 8.3% (n = 27) in those who did not (p = 0.002). Among the 361 patients who underwent BCS alone, patients with USC/VNPI scores of 4–6 had a lower 7-year IBTR rate than those with USC/VNPI scores of 7–11 (6.6% vs. 14.5%, p = 0.015). Similarly, patients in ECOG E5194 cohort 1 criteria had a lower 7-year IBTR rate than those in ECOG E5194 non- cohort 1 (6.5% vs. 14.2%, p = 0.001). Furthermore, estrogen receptor-positive status (p=0.007) and tamoxifen use (p = 0.024) predicted lower IBTR rate in patients who underwent BCS alone. Conclusion Our results indicate that patients with low USC/VNPI scores (4–6) or meeting the ECOG E5194 cohort 1 criteria of breast DCIS who undergo BCS alone may have a lower IBTR rate. The administration of tamoxifen may reduce IBTR in patients with ER-positive breast DCIS who undergo BCS alone. EP-1295 Impact of Alternative Positioning on Heart/Lung Dose: A Dosimetric Follow-up to the IMPORT LOW Trial K. Petras 1 , E.D. Donnelly 1 , J.P. Hayes 1 , P. Rino 1 , W. Matthew 1 , J.B. Strauss 1 1 Northwestern University, Radiation Oncology, Chicago, USA Purpose or Objective As outcomes for early-stage breast cancer patients continue to improve, there has been a focus on reducing treatment-associated toxicity. Recently, the IMPORT LOW trial showed that in select low-risk patients, limiting the treated volume to the surgical bed and surrounding tissue was non-inferior to whole breast radiotherapy (RT) with regard to local control and was associated with small improvements in cosmetic results. All patients were treated in the supine position at free breathing. This analysis aimed to evaluate the impact on heart and lung dose when the field design of the IMPORT LOW trial was paired with an alternative positioning technique of either the prone position or deep inspiratory breath hold (DIBH). Material and Methods The planning CT scans of 30 consecutive early-stage breast cancer patients with available paired image sets at a single institution were identified. The paired image sets were: 1) 10 patients with right-sided breast cancer treated prone and supine; 2) 10 patients with left-sided breast cancer treated prone and supine; 3) 10 patients with left- sided breast cancer treated supine free breathing or

patients gave signed informed consent. The Chi-square and Mann-Whitney tests analyzed differences between ZLC and placebo arms. The Kaplan-Meier test estimated the cumulative incidence of dysphagia and the log-rank test compared results. Univariate Cox regression analysis tested relations between toxicity and prognostic factors. Results All patients completed RT. Treatment arms were matched for age, chemotherapy (CT) and administration of Trastuzumab and hormonal therapy (HT). Overall, the median age was 56 years (range 28-82); 93% received CT before RT, 35% and 70% received, respectively, Trastuzumab and HT during RT. The esophagus median maximum dose (Dmax) was significantly higher in the placebo arm (p=0.005). The median dose to the esophagus was similar in both groups (p=0.76). Nine (45%) patients in the ZLC arm and 20 (100%) receiving placebo developed G1-G2 dysphagia during RT (p<0.0001). No patient developed >G2 dysphagia. Five ZLC patients (25%) and 17 (85%) placebo patients with dysphagia required steroid treatment. ZLC was associated with a later onset and lower risk of G1-G2 dysphagia during RT (cumulative incidence 55.2%, 95%CI: 29.4-81.1 vs 100%, 95%CI: 85.4- 100, p<0.0001) . Univariate analysis showed esophagus Dmax was not a significant risk factor for dysphagia. Conclusion In our phase III trial ZLC significantly prevented or delayed the incidence of dysphagia in breast cancer patients undergoing RT to the draining nodes. Consequently, the need for steroid therapy was significantly reduced. EP-1293 Hybrid intensity modulated radiation therapy for treatment of cancer of left breast after mastectomy EP-1294 Prognosis of patients with breast ductal carcinoma-in-situ who underwent breast-conserving surgery S. Kuo 1 , S.H. Cheng 2 , L. Tseng 3 , Y. Chang 4 , F. Ou-Yang 5 , Y. Kuo 6 , Y. Chang 7 , H. Yeh 8 , C. Hsieh 9 , M. Yeh 10 , H. Chen 11 , W. Chang 12 , S. Chen 13 , C. Huang 14 1 National Taiwan University Hospital, Division of Radiation Oncology- Department of Oncology, Taipei, Taiwan ; 2 Koo Foundation Sun Yat-Sen Cancer Center, Department of Radiation Oncology, Taipei, Taiwan ; 3 Taipei Veterans General Hospital, Department of Surgery, Taipei, Taiwan ; 4 Mackay Memorial Hospital, Department of Surgery, Taipei, Taiwan ; 5 Kaohsiung Medical University Chung-Ho Memorial Hospital, Department of Surgery, Kaohsiung, Taiwan ; 6 National Cheng Kung University Hospital, Department of Surgery, Tainan, Taiwan ; 7 Taipei Tzu-Chi Hospital, Department of Surgery, New Taipei City, Taiwan ; 8 Lotung Poh-Ai Hospital, Department of Surgery, Yilan, Taiwan ; 9 Taiwan Adventist Hospital, Department of Surgery, Taipei, Taiwan ; 10 Chung Shan Medical University Hospital, Department of Surgery, Taichung, Taiwan ; 11 Taipei City Hospital Fuyou Branch, Department of Surgery, Taipei, Taiwan ; 12 Taipei Municipal Wanfang Hospital, Department of Surgery, Taipei, Taiwan ; 13 Changhua Christian Hospital, Department of Surgery, Changhua, Taiwan ; 14 National Taiwan University Hospital, Department of Surgery, Taipei, Taiwan Purpose or Objective We recently demonstrated that California/Van Nuys Prognostic Index (USC/VNPI) score 4-6, Eastern Cooperative Oncology Group (ECOG) E5194 cohort 1 criteria (tumor size ≤2.5 cm, low-to-intermediate grade disease/without necrosis, and surgical margins ≥3 mm), estrogen receptor-positive status, and tamoxifen administration were closely associated with lower ipsilateral breast tumor recurrence (IBTR) in our patients Abstract withdrawn