ESTRO 36 Abstract Book

S630 ESTRO 36 _______________________________________________________________________________________________

Bolognesi 1 , N.G. Di Muzio 1 1 San Raffaele Scientific Institute, Department of Radiotherapy, Milano, Italy 2 San Raffaele Scientific Institute, Medical Physics, Milano, Italy Purpose or Objective To report 5-year outcomes and toxicity in early breast cancer pts treated with whole breast hypofractionated adjuvant radiotherapy(HRT) and concomitant trastuzumab after breast conservation surgery(BCS). Material and Methods From February 2009 to October2011, 442 pts with breast cancer pTis-T2 pN0-N1(up to 3 positive lymph nodes) underwent forward planned intensity modulated HRT to a TD=40 Gy/15 fr at out institution, and reached 5 year median follow up; 31/442 pts presented c-erb B2 overexpression and were treated with HRT and concomitant trastuzumab. Acute toxicity during HRT was evaluated using the RTOG scale, while late side effects were assessed using SOMA-LENT score. Results Patients’ median age was 60,5(28-75)years; tumor breast side: 20 left and 11 right. Histology: DCI: 24 pts; DCI+DCIs: 6 pts; DCI+ LCIs:1 patient; apocrine carcinoma: 1 patient. With a median follow-up of 63,8 (42,5-79,2) mts 3/31 pts (9,7%) presented a local relapse, 2/31 pts ( 6,5%) a lymph nodal relapse and 4/31 pts (12,9%) a distant relapse, confirming the higher propensity for loco-regional and distant relapse of c-erb B2 positive tumors. All pts were alive at the last follow up. Acute toxicity was G0 in 7 pts (22,6%), G1 in 20 pts(64,5%) and G2 in 4 pts(12,9%) with no G3 toxicity. Late G1 edema and hyperpigmentation persisting up to 18 mts after HRT was observed in 7 pts (22,6%). Two persistent late toxicities were registered only in pts treated with FEC chemotherapy before HRT: one G2 fibrosis, starting 36 months after the end of HRT, with breast volume of 1812 cc (cut-off observed in our series: 866 cc), and one G3 teleangiectasy with breast volume of 596 cc. Two cardiac toxicities were registered, both in left sided breast cancers, one in a patient treated with AC x3 cycles+TXT x 12 weeks +trastuzumab x 12 mts, another in a patient treated with FECx5 cycles+ trastuzumab x 12 mts, which presented a mediastinal relapse, treated with salvage chemotherapy. The same patient presented BPCO exacerbations, again after the salvage chemotherapy. While chemotherapy and breast volume were important predictors for acute toxicity, the association of trastuzumab was not statistically significant for both acute and late toxicity at the multivariate analysis. Conclusion HRT after BCS demonstrated good outcomes and low toxicity. The association of hypofractionated radiotherapy with trastuzumab does not increase acute and late toxicity. EP-1160 T4s for T4 small Breast cancer: a new TNM classification subgroup proposal W.S. Zrafi 1 , S. Tebra 1 , H. Ouaz 1 , N. Bouaouina 1 1 Farhat Hached University Hospital, Radiation oncology departement, Sousse, Tunisia Purpose or Objective T4 breast cancer are tumors of any size with direct extension to the chest wall and, or the skin, including inflammatory breast cancer. Non inflammatory T4 breast cancer are a considerably heterogeneous group of tumors with a subgroup of small-sized tumors. Our aim is to evaluate the prognosis of small sized (under 3 cm) non inflammatory T4 breast cancer, comparing them with larger T4 tumors and inflammatory breast cancer.

EP-1158 Vmat radiation induced nausea/vomiting in adjuvant breast cancer radiotherapy: dosimetrical issues. G. Lazzari 1 , A. Terlizzi 1 , B. Turi 1 , M.G. Leo 1 , D. Becci 1 , G. Silvano 1 1 Azienda Ospedaliera SS. Annunziata Presidio Osped, Radiology, Taranto, Italy Purpose or Objective Breast radiotherapy is associated with a minimal emetogenic risk in MASCC/ESMO guidelines. Although the emetogenic potential risk is estimated < 30%, VMAT adjuvant radiotherapy may induce an unexpected acute toxicity defined radiation induced nausea and vomiting (RINV) as we observed in our experience. Aim of our report is to find a correlation between dosimetrical factors and RINV occurrence in our patients (pts). Material and Methods In our institutionfrom January 2013 to May 2016 106 breast cancer pts were treated with adjuvant radiotherapy (RT) in VMAT modality. Al pts had surgery ( conservative or radical). Mean age was 54 years. Neoadjuvant or adjuvant chemotherapy was given in 6 pts and 68 pts respectively (62 pts had high risk emetogenic agents combination, 12 pts had CMF). Left side breasts were treated with in 95 pts, right breast RT occurred in 11 pts. CT planning included all the chest from C6 to D12-L3 vertebrae. PTV consisted of residual breast or chest wall and nodal sites. According ICRU 83 , the prescribed dose was 50 Gy total dose (2 Gy/25) to breast-chest wall and internal mammary chain (10 pts). Supraclavicular nodes (36 pts) were treated simultaneously , 1.92 Gy/25 fractions to 48 Gy total dose. VMAT was planned on treatment planning system Oncentra Masterplan® (collapsed cone algorithm) or Monaco® (Monte Carlo photon algorithm) and consisted of dual arc plan (170°/340° for left breast; 190°/20° for right breast) and 6 MV photons beams. In all the pts we retrospectively contoured on CT planning a volume containing the anatomical structures of emetic vagal-simpatical afferental pathways as the celiac plexus and gastroesophageal junction (GEJCPs). This area was identified as an organ at risk (OAR) for which the total volume, Dmax, Dmean and D1cc were calculated. Univariate analysis with χ 2 , t-test and Pearson covariance were used for statistical analysis. Results On 106 pts, 68 (64%) patients complained acute RINV according CTCAE v.3 criteria G1 nausea in 46 pts (43%), G2 nausea in 13 pts (12%), G1 vomiting in 8 pts (7 %) were recorded. Symptoms occurred at 34 Gy delivered dose (mean 30 Gy, range 20-34). In right side irradiated breasts RINV occurred in 3 pts (27%), in left side RT in 65 pts (60%). RINV was related to a Dmax >10 Gy on GEJCPs (p < 0.005). G1 vomiting and G2 nausea were related to a Dmax > 17 Gy (p < 0.005) and to a Dmax > 15 Gy (p < 0.005) respectively. Radiation breast side, age, systemic therapy, nodal radiation and PTVs volume values were not statistically significant for RINV. Conclusion RINV in breast radiation is not a common acute side effect. VMAT in breast radiation is responsible for a low dose bath to nearest structures as the GEJCPs and this may explain RINV in our cases. A useful constraint as Dmax < 10 Gy on GEJCPs like a serial structure may be considered in VMAT breast planning to avoid RINV. EP-1159 Hypofractionated adjuvant radiotherapy and concomitant trastuzumab for breast cancer: 5-year results M. Pasetti 1 , A. Fodor 1 , C. Sini 2 , F. Zerbetto 1 , P. Mangili 2 , P. Signorotto 2 , I. Dell'Oca 1 , C. Gumina 1 , M. Azizi 1 , A.M. Deli 1 , P. Passoni 1 , N. Slim 1 , C.L. Deantoni 1 , B. Noris Chiorda 1 , S. Foti 1 , A. Chiara 1 , G. Rossi 1 , C. Fiorino 2 , A.