ESTRO 36 Abstract Book

S620 ESTRO 36 2017 _______________________________________________________________________________________________

(49.1%) pts received adjuvant chemotherapy. There were 43 (41%) pts with ECE and 43 (41%) with Grade 3 disease. Complete patient characteristics are included in Table 1 . There were trends toward significance with use of a 3 rd SCV field and pN1a disease (p=0.062), increased tumor size (p=0.062), and positive ECE (p=0.077). The overall rates of 2-year DFS and LRC were 95.1% and 98.9%, respectively. One patient experienced an internal mammary nodal recurrence, 1 contralateral breast tumor, and 2 distant metastases. There were no axillary or ipsilateral breast tumor recurrences. Factors associated with decreased DFS on univariate analysis include Grade 3 disease (p=0.021) and use of a SCV field (p=0.008).

Mean duration of hospitalization was 2.5 days [0-6]. Grade 2 post-operative complications occurred in 19 pts (27%): Abscess: 3pts; Hematoma: 3pts; Seroma: 2pts; Radiation epithelitis: 10pts. Delay in healing was observed in 6 pts. Adjuvant external beam RT after IORT was performed in 3 pts (SNLD+: 2pts; positive margins: 1pt). Hormonal treatment was prescribed in 53 pts (77%). Minimal and mean follow-up were 1 yr and 2 yr, respectively. No local relapse occurred. Two pts died of intercurrent disease. Cosmetic result was assessed in 60pts: excellent: 30pts; good: 28pts; poor: 2pts. Cytosteatonecrosis and cutaneous pigmentation were observed in 7 and 6 pts, respectively. Conclusion IORT in old women is feasible without increasing the rate of post-operative complications. Preliminary results are excellent in terms of local control and cosmesis. EP-1151 Hypofractionated Radiotherapy in breast cancer treatment: A comparison between 3-DCRT and IMRT A. Fiorentino 1 , R. Mazzola 1 , N. Giaj Levra 1 , G. Sicignano 1 , G. Di Paola 1 , S. Naccarato 1 , S. Fersino 1 , U. Tebano 1 , F. Ricchetti 1 , R. Ruggieri 1 , F. Alongi 1 1 Sacro Cuore Don Calabria Hospital, Radiation Oncology Department, Negrar, Italy Purpose or Objective to compare 3-Dimensional Conformal RadioTherapy (3D- CRT) and 4-fields Intensity Modulated RadiationTherapy (IMRT) treatment plans, in terms of target dose coverage, integral dose and dose to Organs at risk (OARs) in early breast cancer (BC) hypofractionated RT. Material and Methods Twenty consecutive patients with early BC, after lumpectomy, were selected for the present analysis. A total dose of 40.5Gy in 15 fractions was prescribed to Planning Target Volume (PTV breast ) of the whole breast, while a simultaneous total dose of 48Gy was prescribed to the PTV of the surgical bed (PTV boost ). For each patient both a 3D-CRT plan with two couples of tangential-fields, and a 4-fields sliding-window IMRT plan were generated. Conformity and homogeneity indexes (CI, HI) were calculated for PTVs. For evaluation of OARs and normal tissue (NT), V 5Gy , V 10Gy and various organ specific V xGy values were analyzed. Results In terms of HI, IMRT (0.18 ± 0.02) was superior to 3D-CRT (0.23 ± 0.02) for the PTV breast (p<0.0001). Both techniques achieved the required dose for the PTV boost coverage, but a significant difference for CI was observed in favour of IMRT (0.9 ± 0.4) compared to 3D-CRT (3.7 ± 4.3) (p<0.0001). With regards to the heart, IMRT improved both mean and near-maximum doses. The inter-patients average of the heart D mean was (1.9 ± 1) Gy for 3D-CRT, and (1 ± 0.8) Gy for IMRT (p < 0.0001). For the analysis of left BC, the inter-patients average of the heart D mean was (2.9 ± 0.8) Gy for 3D-CRT, and (1.7 ± 0.6) Gy for IMRT (p = 0.0005). For the ipsilateral lung, the average of D mean for overall patients was 6.3 ± 1.4 Gy with 3D-CRT, and 4.8 ± 1.3 Gy with IMRT (p<0.0001). The V 25Gy value of the ipsilateral lung was also lower with the use of IMRT (p<0.0001). For the contralateral lung, the inter-patients median of D mean to the contralateral lung was 0.4Gy for 3D- CRT and 0.08Gy for IMRT (p<0.0001). For the contralateral breast, both D mean and D 2% were improved by the use of an IMRT planning technique. The inter-patients average of D mean was (0.3 ± 0.3) Gy for IMRT, while (1 ± 0.5) Gy for 3D- CRT (p <0.0001). For NT , all DVH parameters are in favor of IMRT, except the V 5Gy for which the difference was not statistically significant. The mean value of D mean was 2.2 ± 0.6 for 3D-CRT and 1.5 ± 0.4 for IMRT (p < 0.0001). Conclusion IMRT technique significantly reduced the dose to OARs and NT, with a better target coverage compared to 3D-CRT. Clinical evaluations are advocated.

Conclusion This retrospective analysis of pts undergoing BCS and SLN biopsy with positive SLNs included pts who were underrepresented or excluded from the Z11 trial yet demonstrated comparable rates of LRC and DFS. Nottingham Grade 3 disease and use of a 3 rd SCV field were associated with decreased DFS, though the apparent detrimental effect of SCV treatment was likely due to greater adverse risk factors causing pts to be selected for more intensive treatment. The high rates of LRC and DFS suggest that completion ALND may be safely omitted in this patient population, though prospective data is needed to confirm this finding. EP-1150 Preliminary results of Intra-Operative RadioTherapy in old women with good prognostic features S. Guillerm 1 , E. Bourstyn 2 , R. Itti 1 , I. Fumagalli 1 , V. Martin 1 , L. Cahen-Doidy 2 , L. Quero 1 , S. Giacchetti 2 , C. Cuvier 2 , M. Espié 2 , C. Hennequin 1 1 Hôpital Saint-Louis, Department of Radiation Oncolgy, Paris, France 2 Hôpital Saint-Louis, Breast Cancer Unit, Paris, France Purpose or Objective In women > 65 yrs with good prognostic features (Isolated tumour <3 cm, infiltrative ductal carcinoma (IDC), presence of Estrogen Receptors ER+, pN0), adjuvant RT increases the local control but do not improve overall survival 1 . One possible alternative is to perform RT during surgery to minimize patient’s travels and cost. 1 Hughes, JCO 2013; 31:2382-2387; Kunkler, Lancet Oncol 2015; 16: 266–73 Material and Methods we reviewed our experience with Intra-Operative RadioTherapy (IORT) for this population. All patients had histologically confirmed breast cancer before surgery and were judged eligible for IORT (Isolated IDC less than 3 cm, ER+). Surgery consisted in sentinel lymph node dissection (SNLD) with intraoperative touch imprint cytology and lumpectomy. IORT was performed only in case of negative SLND. It consisted in a radiation dose of 20 Gy delivered with 50 kV photons (Intrabeam®, Zeiss). Results Between October 2012 and February 2015, 76 pts with pre- operative good prognostic features were planned to have IORT. Seven pts did not have it (positive SNLD: 4pts; multifocality: 3pts). For the remaining 69 pts, characteristics were: mean age: 78yrs [67-96]; mean pT size: 15 mm [3-30]; OMS performance status 0-1: 65pts (94%); Charlson Age-Comorbidity Index: Mean: 4.5 [2-9].