ESTRO 37 Abstract book

S740

ESTRO 37

statistically significant differences between irradiated areas. The overall 5y survival of our cohort was 81%. There were statistically significant differences between intrinsic subtypes. Triple negative subtype had the worst prognosis (p=0.010), with 5y survival of 67%. These study had a median follow up of 5.25y. Conclusion In our study, triple negative intrinsic subtype is associated with poor survival. Higher BMI is correlated with greater severity of radiodermitis. The results obtained in our study are in agreement with the existing literature. However powered prospective studies are needed in order to clarify if this subgroup of young patients might benefit from a different approach. Irradiation (Whbi) For Elderly Breast Cancer I. García Ríos 1 , M.J. Garcia Anaya 1 , A. Fernández Forné 1 , I. Domenech Navarro 1 , C. Jodár López 1 , A. Román Jobacho 1 , A. Otero Romero 1 , R. Ordoñez Marmolejo 1 , R. Correa Generoso 1 , J. Gomez-Millan 1 , M.D. Toledo Serrano 1 , C. Castro Garrido 1 , J.A. Medina Carmona 1 1 HOSPITAL UNIVERSITARIO VIRGEN DE LA VICTORIA, RADIATION ONCOLOGY, Málaga, Spain Purpose or Objective Radiotherapy plays an important role in local control, but also improves survival the breast cancer. More than 50% of breast cancer cases occur in women aged 65 years or more, but adjuvant radiotherapy is often omitted in older women because of concerns over treatment burden or logistical obstacles. Treatment decisions concerning elderly patients are often taken on the basis of disease stage, performance status (PS), comorbidities, and even the availability of social support and transportation. Hypofractionation (HF), which is to deliver a lower nominal total dose in larger and fewer fractions. Theoretically, 5 fractions of 5.7 or 6 Gy are predicted to be equivalent to 50 Gy in 25 fractions in terms of tumor control according to the linear quadratic model (assuming α⁄β ratio values of 3.0 and 4.0 Gy, respectively). Objetive To evaluate local control, early and late reactions and disease-free survival of elderly breast cancer patients treated with adjuvant or definitive once-a-week hypofractionated (HF) radiotherapy (RT) Material and Methods Consecutive series of 260 breast cancer patients underwent once-weekly hypofractionated WBRT after BCS or mastectomia or inoperable elderly patients, from January 2006 to Decembre 2016. Patients were primarily selected to take into account older age and/or poor medical condition and/or logistic issues. They were given 32.5 Gy in 5 fractions (6.5 Gy once a week) until October 2011. Subsequently, they were administered 28,5 Gy in 5 fractions (5,7 Gy once a week). The supraclavicular nodes were irradiated with 27.5 Gy (5.5 Gy once a week). All treatments were delivered over 5 weeks. The modification of the fractionation to a lower dose per fraction was chosen according to the approach of the UK FASTer radiotherapy for breast radiotherapy (FAST) randomized trial. Dose was prescribed following International Commission on Radiation Unit (ICRU) recommendations. Results The median aged 78 (35-89) years. 224 (86%) patients underwent breast-conserving surgery, 36 (14%) patients radical surgery and 4 no surgery. The clinical stage distribution was as follows: I in 103, II in 104, III in 50, and IV in 3 patients. Axillary lymph nodes were positive in 41 % of cases. Early skin reactions were tolerable with no documented Radiation Therapy Oncology Group Grade 3 or higher toxicity. Late effects, mainly subcutaneous fibrosis, were recorded in 221 patients, they were EP-1354 Once-Weekly Hypofractionated Breast

both lungs, contralateral breast, heart, liver, esophagus and thyroid. Maximal radiation dose was related to dosimetry of contralateral lung, contralateral breast and heart while laterality was: contralateral lung, heart and esophagus. The modality of primary axillary treatment in these women did not influence the dosimetry of the risk organs with the exception of contralateral breast that showed higher when radiating levels I-IV. However in the multivariate analysis, only radiation therapy modality and maximal dose were significantly associated with this The primary axillary treatment does not influence the dosimetry of the risk organs . Only laterality, max. dose and specially the modality of radiotherapy regimen influence dosimetry in risk organs. EP-1353 Breast Cancer In Young Women: A Retrospective Study C. Sousa 1 , L. Pinto 2 , N. Saraiva 2 , I. Rego 2 , J. Paulo 2 , J. Bastos 3 , M. Mariano 2 , G. Sousa 2 , D. Roda 1 , C. Miranda 1 , G. Melo 1 , M. Cruz 1 , S. Martins 1 , P. Kayla 1 1 Instituto Português de Oncologia Coimbra Francisco Gentil- EPE, Radiation Oncology, Coimbra, Portugal 2 Instituto Português de Oncologia Coimbra Francisco Gentil- EPE, Medical Oncology, Coimbra, Portugal 3 Instituto Português de Oncologia Coimbra Francisco Gentil- EPE, Regional Oncology Registry of the Centre, Coimbra, Portugal Purpose or Objective Breast cancer in young patients represents a particular issue that needs attention. The increasing number of cases and poorer outcomes results due in part to the special clinical-pathological characteristics and the superior risk for disease recurrence and death. Despite an increased risk of local recurrence, age is not a contraindication to breast conserving therapy. The aim of this study is to analyze the characteristics, therapeutic procedures and the profile of radiodermitis (RD) on this group. Material and Methods Retrospective review of patients with breast cancer under 40 years treated between January 2009 and December 2013 in our institution - Portuguese Institute of Oncology of Coimbra. Multivariate statistical analyses and survival evaluation was performed. Results A total of 208 female patients were included, with a median age of 35.9 years (y) (22-39y). At the diagnosis 98.6% had ECOG-PS of 0. 6.3% were bilateral tumors. Gynecological history included a median menarche age of 12.5y (9-17y), 21.1% of nulliparous woman. The median age of first pregnancy was 26,1y (13-36y), 68.8% breastfed. Oral contraceptive were taken in 90.4%. 63% of the patients had BMI<25 kg/m 2 . Histological examination of the tumors revealed mostly invasive ductal carcinoma with grade 2 differentiation in 63% and grade 3 in 19.2% of the cases. Considering the subtype and characteristics of breast cancer we had 24.5% luminal A, 28.4% luminal B non-HER2, 23% HER2 positive and 24.1% patients had triple negative breast cancer. The TNM staging evaluation revealed 4.8% in stage I, 17.8% stage IIA, 33.7% with stage IIB, 36.1% stage III and 9.7% patients were diagnosed in stage IV. 204 patients were submitted to surgery and 70% (n=143) of them performed radiotherapy. Taking into account the absence of 15 registries, 55% (n=69) of patients developed grade (G) 1 RD. Most patients had a body mass index (BMI) of 18,5- 24,9kg/m 2 (n=81), and did not developed RD in 33% (n=27). Patients with BMI 25-29,9kg/m 2 developed G1 RD in 58% (n=19) and G2 RD in 30% (n=10). Patients with BMI 30-34,9kg/m 2 developed G1 RD in 92% (n=12). There is a correlation between BMI and RD, with the most severe RD being in groups of BMI>25kg/m 2 (p=0.006) without parameter. Conclusion