ESTRO 36 Abstract Book

S633 ESTRO 36 2017 _______________________________________________________________________________________________

tumoral bed. Dose constraints were defined by an internal protocol following the QUANTEC directive and more recent reports.HT treatment plans were generated using Tomotherapy HD System commercial planning software (TomoTherapy Inc., Madison, WI). Daily set-up corrections were performed for all patients.Toxicity was reported following CTCAE 4.0. Statistical analysis: The Chi-square and the Mann–Whitney's U-tests compared continuous (age and body mass index) and categorical variables (comorbidity, chemotherapy, hormonotherapy, trastuzumab and chest wall/breast and lymph nodes volumes). Results All patients completed treatment. HT provided good target-coverage for the breast, chest wall and lymph nodes, with respectively mean D90% 47.8Gy and 48.55Gy, mean D95% 46.64Gy and 47.99Gy,mean D98% 45.20Gy and 47.3Gy, and mean V107% 0.65Gy and 0.315Gy. All constraints for OARs were respected (i.e ipsilateral lung: median V5: 70.93 Gy, V20: 24.2Gy and V30: 11.89Gy; contralateral lung: V5: 24.17Gy and V15: 2.15Gy; heart: Dmean 6.6 Gy). G1-G2 acute toxicity developed in 42 patients patients and G3 acute toxicity in only 1 (Table 2). The only risk factor for desquamation and oedema was chest wall/breast volume (p=0.003 and p=0.011respectively). At a median follow-up of 12.5 months (range 2-29), all patients were alive and 41/43 (95.3%) patients were disease-free. Conclusion HT is associated with low acute toxicity and appears suitable for treating the chest wall or breast plus level III and IV draining nodes in patients with breast cancer. EP-1177 Late radiation skin effects after breast conserving surgery: possible predictive clinical factors. A. Romano 1 , A. Rese 1 , E. Toska 1 , L. Faraci 1 , M. Conson 1 , A. Farella 1 , R. Solla 2 , R. Liuzzi 2 , L. Cella 2 , R. Pacelli 1 1 University of Napoli Federico II, Section of Radiation Oncology, Napoli, Italy 2 National Council of Research, Institute of Biostructure and Bioimage, Napoli, Italy Purpose or Objective Previously we have shown that dose to surface and psoriasis were predictive factors for radio-induced acute skin toxicity in patients affected by breast cancer treated with breast conserving therapy (BCT). In this study we assessed in the same group of patients the late skin toxicity, evaluating possible relation with acute skin toxicity, dosimetric and clinical factors. Material and Methods One Hundred Forty patients treated with BCT between 2011 and 2012 in our department were considered for the study. Median age was 57 year (range 32-85). All patients were treated after surgery with 50 Gy to the whole breast delivered with 25 daily fractions in 5 weeks. A boost dose of 10 Gy in 5 days was delivered by electrons to the tumoral bed. Late skin toxicity was assessed by physical inspection during the oncological follow up of the patients and was described and graded according to the RTOG classification. Relation to previous acute skin toxicity, clinical and dosimetric factors was assessed by univariate analysis. Results At a median follow up of 54 months (range 50-60), sixteen patients (11%) developed late skin toxicity. Fifteen grade G1-2 (dyschromia and telangiectasia), while 1 patients had nipple necrosis (G4) at the the site of the surgical scar. Interestingly, no significant relation with previous radio- induced acute skin toxicity was found. Conclusion Our study suggests that late radioinduced skin toxicity appears in a small but significant portion of patients treated by BCT and seems to be unrelated to previous acute skin toxicity.

EP-1178 Breast radiotherapy without nodal irradiation in pT1-2 pN0-1 stage: prognostic factors and outcomes. C. Di Carlo 1 , M. Nuzzo 1 , L.A. Ursini 1 , M. Trignani 1 , L. Caravatta 1 , G. Di Girolamo 1 , M. Di Nicola 2 , D. Genovesi 1 1 Ospedale Clinicizzato S.S. Annunziata, Radiotherapy, Chieti, Italy 2 Biostatistic laboratory, Clinical Sciences, Chieti, Italy Purpose or Objective The aim of study was to evaluate loco-regional recurrence (LRR), overall survival (OS), disease free survival (DFS), prognostic influence of the number of positive lymph nodes and others variables in treatment of early breast cancer patients. Material and Methods From December 2005 to December 2013, 377 female patients with pT1-T2 pN0-N1 were treated in our Radiotherapy Institute and retrospectively evaluated. All patients received conservative surgery with sentinel- lymph node and/or axillary dissection followed by whole breast radiotherapy. According to our institutional protocol nodal region irradiation was not performed. Four cohorts were analyzed according to the number of involved lymph nodes: N0, N1 n1 (1 lymph node +), N1 n2 (2 lymph nodes +), N1 n3 (3 lymph nodes +). Actuarial rates of total LRR, DFS and OS were calculated by the Kaplan-Meier method. Comparisons of clinical and pathologic characteristics between patients groups were calculated using the log-rank test. Results From a total of 377 patients, 284 patients with pT1 tumors and 93 with pT2 tumors were evaluated. The median age was 58 years (range 31-82 years). The absence of involved lymph nodes has been assessed in 276 patients while N1 was reported in 101 patients: 63 N1 n1 , 19 N1 n2 , and 19 N1 n3 . The median follow-up was 4 years with a LRR rate of 3.4% (13/377). In particular a nodal recurrence rate of 1.06% (4/377) was observed: 2 occurred in the axillary region, 1 in supraclavicular region and 1 within internal mammary chain. Estrogen receptor, menopausal status, adjuvant chemotherapy, Her2neu, margin status and grading were not significantly associated with OS and DFS, whereas progesterone receptors were significantly correlated with DFS and tumor size (T>2 cm) with DFS, LRR and OS. Furthermore, a significant correlation between 3 metastatic lymph nodes and OS was found (N1 n3 p-value 0.024, N1 n1 p-value 0.175, N1 n2 p-value 0.369). Conclusion In our series, adjuvant radiotherapy after breast- conserving surgery led to low rates of LRR and high rates of OS and DFS in pT1-T2 pN0-N1 breast cancer patients. Moreover, although the retrospective design, the limited sample size and given the low rate of nodal recurrence, the results observed from our study seem suggest that nodal irradiation in patients presenting 1-3 positive axillary nodes could be not necessary to improve outcome. EP-1179 Target Volume Definition after Lumpectomy for Accelerated Partial Breast Irradiation (APBI) or Boost I.F. Ciernik 1 , A.M. Greiß 2 1 Dessau City Hospital, Radiation Oncology, Dessau, Germany 2 Deaconess Hospital, Department of Surgery, Dessau, Germany Purpose or Objective After tumor resection and surgical manipulation during lumpectomy or oncoplasty, the tumor cavity and the tissue at risk for local relapse is often not clearly definable during radiation therapy planning. Metal clips placed at the thoracic fascia are used to better define the former tumor location. Here we investigated the ability of a