ESTRO 37 Abstract book

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ESTRO 37

Material and Methods In order to reduce the impact of individual anatomical variations, the dosimetric analysis was done in 30 treatment plans with 10 patients in 3 different situations: RT of the breast with boost in the tumor bed; with the inclusion of the SF or with the inclusion of SF and IMC. Contours were made according to the RTOG atlases by the same physician. Planning was made with Three- Dimensional Conformal Radiotherapy with 'Wide Tangents” and 'Field in Field” for homogeneity. Calculations of the increased risks of 2nd lung tumors and Cardiovascular disease with elective lymph node RT were made from the MDs variations found in the 30 planning sessions and their correlation with data published in extensive population databases¹ ¹ Carolyn Taylor, Candace Correa, et al. Estimating the Risks of Breast Cancer Radiotherapy: Evidence From Modern Radiation Doses to the Lungs and Heart and From Previous Randomized Trials. J.C.O. on March 20, 2017. Results RT with the inclusion of SF and IMC compared to breast exclusive RT increased the MD in the lung from 5.0 Gy to 8.1 Gy (Figure 1). RT planning with IMC coverage showed greater heterogeneity (greater V112) just as greater lung V5, V10 and V20 (Figure 2). The PTV IMC incidentally received 73.4% of the dose prescribed in RT plans without the intention of IMC coverage.

the oncology factors and the RT plan of each patient. Special attention must be given to patient who smoke in which RT of drainage will lead to a significant increase in lung MD, as the increased risk of radiation-induced lung cancer may surpass the benefits observed with this treatment. EP-1303 Less is good: once-weekly hypofractionated radiotherapy for early breast cancer in elderly women E. Bonzano 1 , G. Siffredi 1 , M. Guenzi 1 , R. Corvò 1 1 IRCCS Policlinico San Martino and University- Genoa- Italy, Department of Radiation Oncology, Genoa, Italy Purpose or Objective The aim of our study was to evaluate one weekly hypofractionated Adjuvant Radiotherapy (RT) in elderly patients affected by early breast cancer and to report preliminary clinical outcomes, acute skin toxicity and Our study was conducted on 49 patients treated from October 2016 to June 2017. Patients underwent Adjuvant Radiotherapy with a hypo-fractionation regimen: 28,5 Gy / 5 fractions / 1 fraction weekly plus/minus a 2.5 Gy Simultaneous Boost (SIB) on tumour bed in “high risk” cases. Patients were aged over 70 years old (median age 79 y.o., range 72-95), with no severe comorbidities, pT1- 2N0-1a, with different biological subtypes, laterality and size (overall medium). Treatment was delivered in supine position, with tangential fields and constraints of conventional 3D-CRT for lungs and heart; V20=0 for Left Anterior Descending Artery (LADCA) was translated to V12 for radiobiological calculation. Field-in-field technique was used to increasing dose distribution homogeneity. Acute skin toxicity and clinical outcomes were assessed based on RTOG (Radiation Therapy Oncology Group) scales and evaluated before, during each fraction, at the end of RT and at 2, 4 weeks and at 6 months after treatment. Results The median follow-up was 7 months. Clinical o utcome was good, no remarkable changes in breast appearance were detected. Treatment was well tolerated in all cases except a 90 y.o. woman, who interrupted therapy after 3 fractions. Tangential fields were sufficient to achieve satisfactory distribution; SIB was added in 22 patients (45%). Severe grades of cutaneous toxicity (G3 and G4 RTOG) were no observed; grade 2 acute skin side-effects were significantly low. At the end of the treatment only 4 patients (8%) needed topic steroid therapy for G2 dermatitis, which ameliorated within 3 weeks after irradiation; 17 patients (35%) had G1 erythema; 27 women (56%) had no clinical side effects. Two weeks after RT only 15 patients (31%) showed a residual G1 toxicity, spontaneously and quickly resolved. treatment feasibility. Material and Methods

When the increase in MDs is correlated to the increase of LSE risks, it is found that the most important effect of elective lymph node RT is the increased risk of lung cancer, especially in patients who smoke (average increase in absolute risk = 1.38%). The increase in the absolute risk of cardiovascular diseases was below 0.1% in the three sitatuations analyzed. (Table 1)

Conclusion This hypofractionated schedule has proven to be a feasible treatment, with poor acute skin toxicity. Moreover, it represents a facilitation to radiation treatment for elderly patients, who hardly acceed to the hospital, limiting the number of accesses and improving

Conclusion RT of nodal chains increases the heterogeneity of planning and the doses in organs at risk, especially the lungs. In recommending elective lymph node RT, one must consider its risks and benefits, taking into account