ESTRO 37 Abstract book

S739

ESTRO 37

Conclusion Hormonal status, mastectomy, and standard radiotherapy treatment are not related to the resilience. The use of hypofractionated Schedule and the use of no concomitant treatment seems to favor capacity of adaptation and coping models for breast cáncer. The use of anxiolytics or antidepressants contrary to what would be expected, do not favor resilience in breast cáncer. EP-1351 Analyses of doses with deep inspiration breath-hold Vs free-breathing 3D-RT in breast cancer. S. Blanco Parajon 1 , V. Vera Barragán 1 , L. Gómez Heras 1 , D. Rodríguez Latorre 2 , C. Prada García 1 , M.J. Caminero Cuevas 1 , G. Juan Rijo 1 , M.P. Pérez Payo 1 1 Hospital Universitario Central de Asturias, Radiation Oncology, Oviedo, Spain 2 Hospital Universitario Central de Asturias, Radiological Physics, OVIEDO, Spain Purpose or Objective The aim of our study is to compare the dose administered to the heart subvolumes and ipsilateral lung, in breast cancer patients treated with 3D-RT in deep inspiration breath-hold technique (DIBH) Vs free-breathing (FB). Material and Methods 25 locoregional breast cancer patients have been evaluated, 10 right breasts and 15 left breasts. Two CT plans, DIBH-CT and FB-CT, are acquired for each patient. The OARs delineated are: ipsilateral lung (IL), whole heart (WH), pulmonary artery (PA), ascending aorta (AA), superior vena cava (SVC), right coronary artery (RCA), left anterior descending artery (LAD), left circumflex (LC), right atrium (RA), left atrium (LA), right ventricle (RV) and left ventricle (LV). The delivered dose is 50 Gy with opposite tangential fields. Respiratory motion is monitored with the Varian real-time position management respiratory gating system (RPM). We analyze the maximum dose (DM) and the mean dose (Dm) for each structure, V10 in the heart and V20 in the IL, stratifying the patients according to the side and with or without treatment of regional nodes (axilla level III and supraclavicular). The results are analyzed using a one- tailed paired t-test.

Conclusion DIBH reduces the dose to the heart subvolumes and IL globally. There is a significant dose reduction to the heart subvolumes in left breasts, and in the IL in right breasts. In patients with treated regional nodes, the reduction is lower than without them. EP-1352 Dosimetric Variations In Oars In The Radiotherapy Of Breast Cancer Pn1 With Or Without Alnd. M.D. De las Peñas-Cabrera 1 , M. Miguel Hernández 1 , E. Amaya Escobar 1 , P.M. Samper Ots 1 , R. Garcia-Marcos 1 , R. Polo Cezón 1 , M. Medina Cespedes 1 , P. Jimenez López 1 1 Hospital Rey Juan Carlos, Radiation Oncology, Mostoles - Madrid, Spain Purpose or Objective To evaluate the influence of regional nodal irradiation axillary level I-IV vs level III-IV on dosimetry of the risk organs by using a multivariate approach in women with breast cancer, SNB positive to either 1 or 2 nodes and sentinel lymph nodes biopsy alone or ALND. (ACOSOG Z0011 trial). Material and Methods Design: Preliminary report on an ongoing prospective longitudinal cohort study. Of a total of 2707 patients, 639 are breast cancer. 23.60%. There were cT1-2 cN0: 7.82%. In total, 50 women allocated in two groups were studied. 20 were treated by SNB (ACOSOG) and in the remained 30 lymphadenectomy was performed. Since October 2012 we began to apply the recommendation after ACOSOG Z0011 study, and AMAROS, not to perform ALND in patients with infiltrating breast cancer, cT1-T2 cN0, submitted to SNB, which after histological study, were pN1 independent of the type of surgery, conservative or mastectomy. In patientswith either 1 or 2 affected nodes at SNB, we irradiated axillary levels I-IV. Those who undertook ALND, level III-IV were only irradiated. Written informed consent was obtained all patients. Age histology, laterality, cTNM, pTNM, stages, inmunophenotipe were similar in both groups. Dosimetric comparisons of the treatment plans were performed based on the following parameters extracted from DVHs: V5, 10, V20 and mean lung dose (MLD) for the bilateral lungs; V25, V30, and mean heart dose (MHD) for the heart; V10, mean dose for the contralateral breast; esophagus, spinal cord, liver, thyroid, and brachial plexus and maximum dose for the skin. Results were shown as number and percentages for categorical variables (mean and SD) for numerical variables as distribution were normal. Comparisons were done by using chi squared, Student’s t test. Multiple lineal regression was used when several variables showed significance in the univariate analysis. Particularly the influence of laterality, total radiation dose (50 vs 60 Gy SIB), VMAT vs 3DCRT and axillary treatment on dosimetry were evaluated. Significance level was set at 95% (p < 0.05). Results In the univariate analysis the most influencer parameter on dosimetry of the risk organs was radiation therapy mode, associated to significantly higher measurements in

Results We observe a statistically significant reduction (p<0.05) with DIBH in right-sided breast cancer patients, only in Dm and V20 in the IL, and DM in the AA. In the left-sided breast cancer patients, DIBH is associated with a statistically significant reduction in all structures except Dm and V20 in the IL, DM in the LA and Dm in the SVC. In patients with treated regional nodes, a statistically significant reduction is only observed in Dm and V10 in the heart, V20 in the IL and Dm in the LV. Without treated regional nodes, DIBH is associated with a statistically significant reduction in all structures except DM in the RCA, AA, RA and LA, DM and Dm in the SCV.