Abstract Book

S707

ESTRO 37

Results Mean age was 51 years (31-75) with 84 patients younger than 60. After a median follow-up of 55 months (12-97) there were three ipsilateral relapses, two as a new DCIS and one as an invasive carcinoma. We had no nodal relapses and curiously, one patient developed distant metastases without evidence of loco regional relapse. Breast cancer specific survival was 100% and the mean time from the first diagnosis and the relapse was 43 months. Acute radiodermatitis was absent or grade 1 in 89.5% of the patients. After HDR-BT, two patients suffered from moderate bleeding that was resolved with conservative measures and did not require hospitalization, surgery or transfusion; one patient had a mastitis successfully treated with antibiotics. In the long term, grade 3 fibrosis was identified in two patients. Conclusion In our experience, hypofractionated adjuvant IMRT plus a HDR-BT boost after a conservative surgery in DCIS has proven to be safe and effective, with low rates of local relapses and side effects. EP-1287 Regional nodal irradiation vs axillary lymph node dissection in breast cancer: a meta-analysis. G. Viani 1 , F. Arruda 2 , A. Hamamura 2 , A. Faustino 2 , F. Guimarães 2 , V. Bighetti 2 , D. Pereira 2 1 School of Medicine of Ribeirão Preto-USP- São Paulo- Brazil, Radiation oncology department, Marilia, Brazil 2 School of Medicine of Ribeirão Preto-USP- São Paulo- Brazil, Radiation oncology department, Ribeirão Preto, Brazil Purpose or Objective Objective: To compare the treatment outcomes in patients with clinically negative (cN0) and positive sentinel lymph node biopsy (SLNB) breast cancer undergoing to axillary lymph node dissection (ALND) or regional nodal irradiation (RNI). Material and methods: A systematic review and meta-analysis of randomized clinical trials (RCT) comparing ALND versus RNI in patients with cN0 and positive SLNB. The primary end- point was overall survival (OS), disease free survival (DFS), axillary recurrence, and lymphedema rate. Results Two trials (1372 patients) compared ALND with RNI in cN0 breast cancer, and other two RCTs (1899 patients) compared ALND with RNI in positive SLNB. For OS, no significant difference comparing ALND vs. RNI in cN0 was observed, (RR=0.98 CI95% 0.9-1.08, p=0.74). In the group with positive SLNB, two trials compared ALND vs. RNI, RR=1.01 (CI95% 0.96-1.07, p=0.68). For DFS, no significant difference comparing ALND vs. RNI in cN0, RR=0.97(CI95% 0.88-1.06, p=0.44) and positive SLNB, RR=0.92 (CI95% 0.83-1.01, p=0.07), was seen. The RR comparing ALND vs. RNI for axillary recurrence was 0.94 (CI95% 0.70-1.26, p=0.89) for cN0 and RR=0.76 (CI95% 0.32-1.82, p=0.54) for positive SLNB (figure-1). Two trials evaluated the rate of lymphedema in positive SLNB, a significant difference was observed in favor of RNI, 23 % vs 9.8% (p=0.0001), figure-2. Conclusion The present study is the first meta-analysis to evaluate the role of RNI in cN0 and positive SLNB breast cancer patients. Our data confirm that RNI produces similar outcomes than ALND in both clinical scenarios. However, RNI reduces the risk of lymphedema significantly in positive SLNB patients. Although a subgroup analysis to evaluate the real value of RNI on mastectomy in patients with positive SLNB was not possible, the low risk of recurrence permits us to affirm that ALND can be avoided in this setting. Patients with a similar risk to the AMAROS/OATOSOR for the additional lymph node should be submitted to RNI to avoid the late effects of ALND.

Subjective aesthetics assessed from 1 to 5 points was 3.8 and 4.5 in global satisfaction/quality of life (QoL). Only one patient, in view of the final results, would have taken the decision to defer reconstruction. We didn't observe dosimetric disturbances caused by the metallic membrane of the expander higher than 5% of the prescribed dose, which were minimized using field in field compensators. There was only a local relapse - outside the quadrant of the membrane- 40 months after the PMRT. Conclusion Assuming that the delayed reconstruction is the standard, we think that if we have to irradiate a patient who has already started the reconstruction process or wants it, there is no reason to discard this approach. As we have shown, it provides a good QoL with acceptable aesthetic results, but all the management should be monitored in a multidisciplinary team and discussed in detail with the patient. EP-1286 Adjuvant hypofractionated breast radiotherapy plus brachytherapy boost for ductal carcinoma in situ A.A. Diaz Gavela 1 , E. Del Cerro 1 , F. Counago 1 , F. Marcos 1 , J. Castro 2 , H. Pérez 2 , C. Rodríguez 3 , C. Fernández- Chacón 4 1 Hospital Quiron Madrid, Radiation Oncology, Pozuelo de Alarcon- Madrid, Spain 2 Hospital Quiron Madrid, Radiophysics, Pozuelo de Alarcon- Madrid, Spain 3 Hospital Quiron Madrid, Gynecology Department, Pozuelo de Alarcon- Madrid, Spain 4 Hospital La Zarzuela, Medical Oncology, Madrid, Spain Purpose or Objective For years, conventionally fractionated whole-breast (WB) radiotherapy after breast conserving surgery has traditionally been the standard treatment for invasive breast cancer. This situation has changed since the publication of randomized clinical trials that showed an equivalence between classic and hypofractionated (HF) schemes in terms of disease control and side effects, and proving that this approach was an economically attractive option. However, until recent times, conventional fractionation has remained to be the standard in the treatment of ductal carcinoma in situ (DCIS). Few groups in Europe have showed their experience in the HF management of patients with DCIS and to our knowledge, no group has reported their experience in the HF management of DCIS associating a brachytherapy boost on the tumor bed after knowing, as it has been recently reported, that administering a RT boost confers a statistically significant benefit in decreasing local recurrence across all DCIS age groups, similar to that seen in invasive cancers. Material and Methods Between September 2009 and November 2016, 107 patients received a field-in-field WB-IMRT after a conservative surgery according to the START-B trial scheme (40.05Gy/15fr) plus a High Dose Rate Brachytherapy (HDR-BT) boost over the tumor bed. The boost was administered in a single dose of 7Gy in 7 patients and 8Gy in 100. The HDR-BT treatment was calculated using the modified Paris system and the implant was performed on local anesthesia without hospitalization. Toxicity was analyzed using the Common Terminology Criteria for Adverse Events. Patients were retrospectively reviewed using the data collected in the medical records. Despite this, the toxicity assessments are homogeneous and comparable, since only two clinicians of the Radiation Oncology Service are dedicated to the follow- up of breast cancer patients and have similar criteria when evaluating and recording toxicity.