ESTRO 36 Abstract Book

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needed to validate these results with exclusion of possible selection bias. EP-1175 Impact of body-mass index on setup displacement in patients with breast cancer Y.C. Tsai 1 , C.Y. Chen 2 , J.T. Tsai 1 1 Taipei Medical University-Shuang Ho Hospital, radiation oncology, New Taipei City, Taiwan 2 Wan Fang Hospital- Taipei Medical University, Radiation oncology, Taipei, Taiwan Purpose or Objective To determine the impact of body-mass indexfactors (BMIF) on daily setup variations for patients with breast cancer treated with adjuvant radiotherapy with daily image guidance.before radiotherapy and changes duringradiotherapy on the magnitude of setup displacement in patients with breast cancer. Material and Methods The clinical data of 117 patients with breast cancer was analyzed using the alignment data from daily on-lineon- board imaging from image-guided radiotherapy between 2013 and 2015. All patients received cone beam computed tomography(CBCT) at the first 5th fraction, then once per week at least. BMFs included body weight, body height, and thecircumference and bilateral thickness of the neckThe shifts of each fraction were collected in superior- inferior (SI), anterior-posterior (AP), and medial-lateral (ML)directions respectively, and the absolute distant of shifts was also calculated. The shifts of patients were grouped by factors of BMI, body weight, height, age, operation method and acute toxicities respectively. For grouping of BMI,body weight and height, the median values were used as cut off. The impact of factors as assessed by compare the shifts using independent t-test within each groups. Results Median BMI was 24.3, and median body weight was 59kg. A higher body weight before radiotherapy correlated with a greater shift in ML(p =0.0088 ), and SI(p = 0.0004) direction. A larger BMI( ≧ 24.3) was associated with a greater shift in SI (p = 0.0005) direction. Comparsion of patients undergoing breast-conserving surgery(BCS) and modified radical mastectomy(MRM), BCS group was associated with a larger shift in SI and ML(p=0.028 and p=0.0051, respectively). Conclusion Larger body weight( ≧ 59kg, larger BMI( ≧ 24.3) and BCS may be a significant risk factor for daily shifts. EP-1176 Helical tomotherapy in chest wall/breast and draining node irradiation after breast cancer surgery V. Lancellotta 1 , M. Iacco 1 , S. Chierchini 1 , E. Perrucci 1 , I. Palumbo 1 , L. Falcinelli 1 , S. Saccia 1 , S. Nucciarelli 1 , A. Milletti 1 , C. Aristei 1 1 Ospedale Santa Maria della Misericordia, Radiation Oncology, Perugia, Italy Purpose or Objective Three dimensional conformal radiotherapy (3DCRT) to the chest wall/breast and draining nodes has long been standard treatment for patients at high-risk of relapse after mastectomy or conserving surgery (BCS). Given the complex target shape, other radiotherapy techniques such as intensity modulated RT (IMRT), volumetric modulated arc therapy (VMAT), helical (HT) or direct (DT) tomotherapy were developed. The present study evaluated the toxicity of HT for treating the chest wall or breast plus level III and IV lymph nodes after mastectomy or BCS. Material and Methods From January 2013 to August 2016, 43 consecutive patients with breast cancer underwent helical

tomotherapy . Table 1 reports their demographics and clinical details. Computed tomography (CT) scans without contrast medium were acquired with patients supported by breast board in the treatment position. CT data were acquired with 2.5 mm slice thickness and were transmitted to the Pinnacle 3 TPS V9.8. One radiation oncologist contoured the clinical target volume (CTV) i.e. chest wall or breast, level III and IV lymph nodes and organs at risk. The chest wall was not expanded to obtain the planning target volume (PTV); the breast and nodes were expanded 0.5 cm in all directions to obtain the PTV breast and PTV ln. Dose prescription was 50 Gy to the PTVs in 25 fractions. In 7 patients treated with BCS a simultaneous integrated boost (SIB) was delivered to the 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