ESTRO 36 Abstract Book

S642 ESTRO 36 _______________________________________________________________________________________________

Purpose or Objective The risk of breast failure after breast-conserving treatment is two-fold higher in invasive carcinoma with positive surgical margins than in free margins, (between 12 and 34% at ten years) (1). A new resection is recommended, with risk of fair cosmetic result, or mastectomy. With close margin total dose should be higher to avoid local recurrence. Twenty years ago, we started with a high dose rate (HDR) boost after whole breast irradiation in cases with close or positive margin. We review the long-term outcome in these high risk cases Material and Methods Between 12.1996 and 12.2011, 248 patients were included, with a median age of 55 (22-90). Mean FU 127 months. By T stage 179 T1, 62 T2 and 6 T3. By margin status, 120 was positive, 76 close until 2mm, 52 close >2mm and <5mm. All of them were treated with whole breast irradiation (WBI) 50Gy plus HDR boost with 3 fractions of 4.4Gy to 85% isodose in two days, with rigid needles. The contour of CTV was decided by clinical assessment, no CT planning was used. Chemotherapy was used in 52%, and hormonal treatment in 76%. Survival was calculated by Kaplan Meyer method. Results In the whole population, actuarial breast failure at 10 and 15 years was 6.5% and 11.6%. With positive margin: 6.8% and 14.8%, with close margin ≤2mm: 9.8% and 9.8%, with margin >2mm <5mm, 2% and 2%. By age, in 90 patients aged 50 or younger, was 11.9% and 17.8%, between 51-70, 3.8% and 8.2%, and no failures over 70. In young women under 50 with positive margin, breast recurrence was 13.1% and 24% at 10 and 15 years. By T stage, no differences between T1 and T2, no failures in T3. No differences if margin was due to invasive carcinoma or DCIS, in G3, or depending on hormonal receptors. Fibrosis or induration were registered in 26.7%, breast edema 6.5%, volume reduction 6.5%, telangiectasia 3.4%, hyperpigmentation 2.1%. Cosmetic outcome was excellent/good in 85.8%. Conclusion Long-term breast control of patients with positive or close surgical margin using WBI plus a HDR boost is similar to that achieved with free margins in the EORTC 22881-10882 trial, in all groups of age, but in young women with positive margin where a new resection is recommended. This approach is useful to avoid a second intervention, in women over 50 with positive surgical margin, or with close margins in all ages. (1) Guinot JL, et al. Breast-conservative surgery with close or positive margins: can the breast be preserved with high- dose-rate brachytherapy boost? Int J Radiat Oncol Biol Phys 2007; 68:1381-87 EP-1185 Post-operative Irradiation after Nipple- Sparing or Skin-Sparing Mastectomy: An International Survey G.N. Marta 1,2 , P. Poortmans 3 , R.A. Audisio 4 , R. Freitas Junior 5 , A.C. De Barros 6 , J.R. Filassi 7 , S.M. DeSnyder 8 , S. Meterissian 9 , T.A. Buchholz 10 , T. Hijal 11 1 Hospital Sírio-Libanês, Radiation Oncology, São Paulo, Brazil 2 Instituto do Câncer do Estado de São Paulo ICESP - Faculdade de Medicina da Universidade de São Paulo, Radiation Oncology, Sao Paulo, Brazil 3 Radboud university medical center, Radiation Oncology, Nijmegen, The Netherlands 4 University of Liverpool, Surgical Oncology, Liverpool, United Kingdom 5 Universidade Federal de Goias, Surgery, Goias, Brazil 6 Hospital Sírio-Libanês, Surgery, Sao Paulo, Brazil 7 Faculdade de Medicina da Universidade de São Paulo FMUSP, Breast Surgery Division, Sao Paulo, Brazil 8 The University of Texas MD Anderson Cancer Center,

Surgical Oncology, Houston, USA 9 McGill University Health Centre, Surgery, Montreal, Canada 10 The University of Texas MD Anderson Cancer Center, Radiation Oncology, Houston, USA 11 McGill University Health Centre, Radiation Oncology, Montreal, Canada Purpose or Objective Skin sparing mastectomy (SSM) and nipple-sparing mastectomy (NSM) have entered routine surgical practice for breast cancer, though their oncologic safety has not been established in randomized controlled trials. The aim of this study was to evaluate breast surgeons’ opinions concerning the indications of post-operative radiation after SSM and NSM. Material and Methods Breast surgeons from North America, South America and Europe were invited to contribute in this study. A 22- question survey was mailed to participating breast surgeons to evaluate their opinions. the indications of post-operative radiation after SSM and NSM. Results A total of 252 breast surgeons answered the questionnaire. Most of them had at least 10 years of post-residency practice. The majority of breast surgeons affirmed that post-operative radiation should be performed in early- stage (stages I and II) breast cancer for patients who present with risk factors for relapse after SSM and NSM (85.0% and 81.0%, respectively). They considered age, lymph node involvement, tumor size, extracapsular extension, involved surgical margins, lymphovascular invasion, triple negative receptor status and multicentric tumor as major risk factors. Considering tumor size, lymph node involvement and age as recurrence risk factors, the most-often suggested cut-off thresholds of those features were 5 cm, > 3 lymph nodes and 40 years old, respectively. Considering that after SSM and NSM, residual breast tissue can be left behind, the residual tissue considered as acceptable in the context of an oncologic surgery were 1 to 5 mm and 6 to 10 mm for 55% and 21% of the responders, respectively. There is no consensus for the necessity of evaluating residual breast tissue through breast imaging. Conclusion Although the indications of post- operative radiation therapy after SSM and NSM are not well defined, all standard relapse risk factors were considered as important, by surgeons, with regards to referring for post-operative radiation therapy. EP-1186 Real-time intrafraction motion in breast radiotherapy using an optical surface scanner D. Reitz 1 , S. Schönecker 1 , P. Freislederer 1 , M. Pazos 1 , M. Niyazi 1 , U. Ganswindt 1 , C. Belka 1 , S. Corradini 1 1 LMU University of Munich, Radiation Oncology, Munich, Germany Purpose or Objective Intrafraction motion is of special interest in modern breast cancer radiotherapy. Respiratory motion during intensity- modulated radiotherapy (IMRT) can cause problems in inadequate planning target margins or IMRT delivery. To date, only few data exist on real-time measured intrafraction motion in breast cancer patients. Continuous surface imaging using visible light offers the possibility to monitor patients’ movements in 3D-space without any additional radiation exposure. Material and Methods We observed thirty-one patients during 629 fractions that underwent postoperative radiotherapy following breast conserving surgery or mastectomy. During each treatment session the motion of the patient was continuously measured using the Catalyst TM optical surface scanner (C-