Abstract Book

S723

ESTRO 37

All surgeons had training as well as a supervision period prior to doing the procedure individually. Adjuvant therapy including EBRT, chemotherapy or hormonal therapy was administered according to the final pathologic results and oncologic guidelines. Patients were followed registry to determine oncologic events, short- term toxicity and overall cosmesis. Results Of 3,702 patients, 237 cases (6.4%) were referred for IORT. 176 patients (74.3%) were eligible and treated with IORT. Median follow-up was 18.8 months (range 2-36 months). One patient developed local relapse. There were no breast cancer related metastases or deaths. The average hospital stay was 1.2 days and wound healing time was 7±2 days. Seven patients (4.8%) developed postoperative infection. Two patients needed surgical re- excision. There was no observed excess need for pain medication. The evaluation of cosmetic outcome showed that 82% of the patients graded as excellent or very good while 18% patients graded it as good. Eight patients (4.5 %) needed additional external radiation therapy. We analyzed the reasons for non-treatment in the 25.7% of referred patients. We found that 36% of these did not meet the eligibility criteria, 17% had positive SLN during surgery and IORT was aborted, 23% of the patients were eligible but the reason for non-treatment was economic due to insurance refusal to pay the cost, in 3% it was due to a technical problem in the Intrabeam machine and in 14% it was due to other miscellaneous reasons. Conclusion For early-stage breast cancer patients, intraoperative radiotherapy after breast-conserving surgery in a private based hospital, if performed adhering to a peer reviewed protocol is both safe and reliable and results in very acceptable outcomes. With the larger emerging experience patient selection for IORT should be less restrictive. Patient and physician education is needed in order to increase awareness of this modality. Insurers should be involved in the costs and benefits of this procedure. EP-1318 Hypofractionationated RT in Breast Cancer: Early Experience from a tertiary care centre in India J. Bhattacharya 1 , M. Mukherjee 1 , T. Shahid 1 , R. Rajan 1 , R. Talukdar 1 , J. S 1 , A. Samanta 1 , P. Vijayaraghavan 1 1 Apollo Gleneagles Hospital- Kolkata, Radiation Oncology- Cancer Block- 1st Floor, Kolkata, India Purpose or Objective In India, the most common radiotherapy fractionation used for Breast Cancer is conventional fractionation (50Gy in 25 fractions over 5 weeks) followed by boost to the tumor bed for patients who undergo Breast Conservation.A good number of evidence is emerging on hypofractionation in breast cancer. But data on similar practice is lacking from India. Breast Cancer contributes to a significant proportion of Radiotherapy patients at most centres. Hypofractionation can be a good option in such centres for optimal utilisation of resources. We report the results at our centre with START B type of fractionation. Material and Methods From January 2014 to December 2016, non-metastatic breast cancer patients undergoing Modified Radical Mastectomy (MRM) or Breast Conservative Surgery (BCS) were treated using hypofractionated adjuvant radiotherapy. 3DCRT planning was used to deliver 40Gy in 15 fractions over 3 weeks to the Chest wall or Whole Breast with or without Supraclavicular Fossa (when indicated) for MRM and BCS patients respectively followed by electron boost (12.5 to 15 Gy in 5 to 6 fractions) to the tumor bed in the latter group. RTOG Skin toxicity and Cosmesis outcome were assessed during and after completion of Radiotherapy and at subsequent follow-up visits. Cosmesis outcome was assessed by

Havard Scale. Recurrences and Deaths were also documented and preliminary survival analysis was done at median follow up. Results Out of 171 patients, 93 patients underwent BCS and 78 patients had MRM. Mean age of the entire population was 50 years. T2 was the most common tumor stage, (58% and 42% for BCS and MRM group respectively). Invasive Ductal Carcinoma (IDC) was the most common entity seen (90%). The median Nottingham Prognostic Index Score was found to be 4.6 for the BCS as compared to 5.58 for the MRM. Triple Negative Breast Cancer was 28.1% among all patients. 31.2% patients in the BCS group and 44.9% patients in the MRM group received Neoadjuvant Chemotherapy. Grade I Skin toxicity was the most common acute toxicity observed at the end of Radiotherapy, 93.5% in BCS group and 100% in the Mastectomy group. 6 (6.5%) patients in BCS group developed Grade II toxicity at this time. At three months, the incidence of Grade I toxicity was reduced to 89.2% and 85.9% for BCS and MRM respectively. At 6 months and 1year, persistent grade I toxicity was observed in 26.9%, 14% and 15.4%, 9% patients in BCS and MRM group respectively. Excellent and good cosmetic outcome was noted in 66.7% and 32.2% respectively on follow up for BCS group. Median follow up was 15 months. 25 patients (14.6%) developed distant metastasis. At 15 months RFS and OS were 87.2 % and 87.5% respectively. Conclusion Hypofractioanated Radiotherapy in breast cancer is well tolerated with acceptable skin toxicity and excellent to good cosmetic outcome in Indian population. This strategy can be applied to utilize our resources optimally. This is an on-going study to assess the long term results. EP-1319 Long-term results of partial-breast-IORT or IORT-boost: a 10-year mono-institutional experience. M. Pazos 1 , S. Mehl 1 , B. Kost 2 , V. Bodungen 2 , S. Schönecker 1 , D. Reitz 1 , P. Rogowski 1 , T. Vallbracht 2 , R. Würstlein 2 , N. Harbeck 2 , C. Belka 1 , S. Corradini 1 1 LMU Munich, Radiation Oncology, Munich, Germany 2 LMU Munich, Obstetrics and Gynecology, Munich, Germany Purpose or Objective After conservative surgery in early-stage breast cancer (BC) 90% of recurrences occur in the same quadrant as the primary tumour. This data supported the adoption of partial breast irradiation (PBI) in selected BC patients. In recent studies, intraoperative radiotherapy (IORT) using Intrabeam (Carl Zeiss Meditec, Germany) had shown slightly higher local recurrence rates compared to whole breast irradiation (WBI) with similar acute toxicity and survival on short-term 5-year follow-up. Aim of the present analysis was to report long-term results of our 10-year Intrabeam IORT experience as PBI and as anticipated boost. Material and Methods Between 2006 and 2016, 214 patients were consecutively treated with IORT at our Institution. Two time-periods were compared: before and after the publication of the TARGIT-A-Study in 2010. Local recurrence rates, survival and toxicity data were estimated. CTCAE classification was used for acute (0-30 days post-IORT) and late (>3 months) Events. Results In the first observation period between 2006 and 2010, 49 patients were treated with a median age of 63.6 years and a median follow-up of 8.1 years. 80 % of cases were included in the TARGIT-A-Study and 57.4% of patients received IORT as a boost. In the period between 2010 and 2016, 165 patients (median age 64.3 years) received IORT and the median follow-up was 3.1 years; 5.5% of patients were in the TARGIT-A trial and 73.3% received an additional WBI. Overall, 4.2% of patients were lost to