Abstract Book

S722

ESTRO 37

1 Institut Curie, Radiation oncology, Paris cedex 05, France 2 University Claude Bernard Lyon 1- INSERM 1052- CNRS 5286, Cancer Research Center of Lyon-, Lyon, France 3 Ruijin Hospital, Radiation oncology, Shangai, China Purpose or Objective is to evaluate our experience in terms of local control, survival and adverse effects in patients treated by adjuvant Helical Tomotherapy (HT) for not metastatic breast cancer (BC). Material and Methods A retrospective study of all patients treated by HT between 2009 and 2015 was done. Patients excluded were: breast implants, advanced or metastatic breast cancer, recurrences. All patients received breast+/-boost or chest wall irradiation and most of them with lymph node irradiation. The dose constraints for organs at risk (OAR) were defined using optimization scale developed in our Department. Evaluation of early and late toxicity was done using Common Terminology Adverse Criteria Events v.4.0 during the weekly and the follow-up clinics. Results We studied 179 consecutive patients with 194 treated breasts with adjuvant HT. Median follow-up was 38.1 months (7.4-78.2). The median age was 53 years (25-76). Chemotherapy was administered to 83% of patients: adjuvant in 61% and neoadjuvant in 39%. All 133 RH + tumours received hormonal therapy. As concurrent treatment, apart from trastuzumab monotherapy, 6 patients received systemic therapy concomitant to RT, including FUN chemotherapy (5FU + vinorelbine) in 4 cases. The HT was generally well tolerated with mostly grade 1 and 2 skin reactions and esophagitis. Only 3% experienced grade III early skin reactions. At last follow- up, there were 2 local recurrences, 1 regional LN recurrence and 6 with metastatic progression. The 5-year progression-free survival (PFS) was 90.5% (95%CI 84.2- 97.3) Conclusion HT can be used for a well selected group of breast cancer as bilateral tumours, complex anatomy and target volumes where the conventional radiation therapy techniques cannot ensure an optimal dose distribution with good efficacy and tolerance. Longer follow-up is necessary to confirm and validate these results. EP-1317 Early results of implementation of IORT with INTRABEAM for early breast cancer in a private hospital Y. Tova 1 , M. Pappa 2 1 Assuta Medical Center, Radiation Therapy, Tel Aviv, Israel 2 Assuta Medical Center, Surgery, Tel Aviv, Israel Purpose or Objective Results of TARGIT trials increased clinical interest in intraoperative radiotherapy (IORT) during breast- conserving surgery (BCS) in early breast cancer and thus we have evidenced an increase in its use. At Assuta Medical Centers we implemented this treatment in a private hospital setting where it is in use by multiple surgeons. This work reviews surgical oncology guidelines, treatment protocol and outcomes for breast cancer patients who received IORT as their sole radiation treatment at our hospital. Material and Methods Between August 2014 and October 2017, 3702 breast cancer patients underwent breast conserving surgery at Assuta Medical Centers, Tel Aviv , Israel. 176 early-stage patients received BCS and IORT with the Intrabeam system. Since there was a large diversity of surgeons, each patient was seen by a radiation oncologist and then presented at a multidisciplinary tumor board which included surgeons, radiation oncologists, medical radiologists, pathologist and breast imaging radiologists.

Material and Methods Preclinical studies and initial non-randomised clinical trials in Japan have suggested a significant radiosensitising effect of KORTUC, with published complete response (CR) rates of 79-100% at up to 5 years follow up in over 100 patients. In comparison, a contemporary Japanese cohort of 108 patients receiving systemic treatment and RT alone recorded a CR rate of 36%. A UK Phase 1 trial (n=12) commenced at our institution in January 2017 to confirm safety of this treatment (ClinicalTrials.gov NCT02757651). Patients with locally advanced breast cancer ≥3cm were recruited. A radiotherapy schedule of 36Gy in 6 twice- weekly fractions, or 49.5Gy in 18 daily fractions was selected according to performance status. Twice-weekly intratumoural KORTUC injections were administered (1 hour prior to RT) under ultrasound guidance, commencing in the second week of RT. 2.5-5mls KORTUC was injected, depending on tumour size. Skin toxicity was recorded at baseline, and then weekly until 4 weeks post radiotherapy. Ultrasound (US) assessment was performed at 3 and 6 months post treatment. Results 7/12 patients (5 female, 2 male) have been recruited; 5/7 have completed treatment. The mean age of the patients was 75 years (median 78, range 53-89). 5 patients had ER+/HER2-, 1 patient ER+/HER2+, and 1 patient ER-/PR-/HER2- disease. 4 patients received 36Gy/6# and 1 patient 49.5Gy/18#. 6/7 received concurrent endocrine therapy. KORTUC was well tolerated with 100% compliance. 3/5 patients experienced Grade 1 local tumour pain during injection not lasting more than 30 minutes. Skin toxicity (CTCAE v4.03) was scored as G0 in 1, G2 in 2, and G3 in 2 patients (treated with bolus). All resolved to

Volume reduction* from baseline (%)

Baseline measurement (mm)

3-month US (mm)

6-month US (mm)

Patient

40x27x30 (SD) 28x9x31 (PR) 32x17x25 (PR) 17x20x17 (PR) 31x9x16 (PR)

36x22x25 (PR)

1

42x28x31

45

2

55x30x47

-

90

26x25x17 (PR) 22x20x12 (PR)

3

41x25x42

74

4

29x30x30

80

5

43x17x14

-

56

*assuming tumour is hemi-ellipsoid shape, volume calculation by: π/6 x length x width x height Conclusion In our experience, KORTUC in combination with external beam RT is a safe and well tolerated treatment, with no additional toxicity compared to standard RT alone. Phase 1 is expected to complete recruitment by January 2018 and will be followed by a multicentre randomised Phase 2 trial (84 patients) comparing RT +/- KORTUC. EP-1316 The use of Helical Tomotherapy in early stage breast cancer: indications, tolerance, efficacy. A. Arsène-Henry 1 , J.P. Foy 2 , M. Robilliard 1 , H.P. Xu 3 , L. Bazire 1 , D. Peurien 1 , P. Poortmans 1 , A. Fourquet 1 , Y.M. Kirova 1