ESTRO 2020 Abstract book

S367 ESTRO 2020

We conducted a multicenter comprehensive systematic electronic data collection cohort study based on a standardized structured end of treatment evaluation and treatment characteristics form integrated in Mosaiq®. Three comprehensive cancer centers used a common evaluation form for breast cancer patients treated with radiotherapy with 7 items (WHO status, weight, acute toxicities scored according to CTCAE V4). Results Between January 2016 and September 2019, 2512 patients, median age, 62 years [24-96], were assessed. Most patients (96.8%) had a WHO status 0-1 with 69.9% RE+, 59% RP+ and 70.6% HER2-. Most had non metastatic disease (79.8%) and 57% were N0. Moderate hypofractionation (2.67 Gy/fr) was used in 676 patients (26.91%) and normofractionation (2 Gy/fr) in 1812 patients (72.17%). Overall acute toxicities were mild with no grade 4 or 5. Most patients had a numerical rating scale for pain 0-2/10 (90.6%). Dermatitis were lower with hypo than normofraction (grade 2-3: 9.1% versus 36.1% p<0.05). Breast edema was rare with grade 0 in 70.6% and 61.4% (p<0.05) of hypo and normofractionated treated patients respectively. Hyperpigmentation grade 0 was experienced by 78.1% and 43.7% (p<0.05) of patients treated with hypo and normofractionation, respectively.

Conclusion This study supports the equivalence of radiation therapy alone, adjuvant endocrine therapy alone and the combination of both in low-risk breast cancer patients over 70 treated with breast-conserving surgery. Receiving no adjuvant therapy is associated with poorer outcomes. As many of these patients are candidates for Accelerated Partial Breast Irradiation, the treatment decision could be between 5 years of endocrine therapy and 5 days of radiotherapy. When deciding about adjuvant therapy in this patient population, patients and clinicians should weigh toxicity and convenience of adjuvant endocrine therapy alone versus adjuvant radiation therapy alone, on a case-by-case basis, to guide treatment decisions. PH-0598 Normo versus hypofractionated whole breast irradiation: Are real life data what we expect? S. Guihard 1 , C. Petit 2 , J.B. Clavier 1 , L. Jung 1 , S. Servagi Vernat 3 , S. Bellefquih 3 , A. Ruffier 4 , G. Brusadin 2 , E. Remi 5 , S. Rivera 6 1 Paul Strauss, Radiotherapy, Strasbourg, France ; 2 Gustave Roussy, Radiotherapy, Villejuif, France ; 3 Jean Godinot, Radiotherapy, Reims, France ; 4 Institut interrégional de cancérologie- centre Jean-Bernard, Radiotherapy, Le Mans, France ; 5 Elekta, Radiotherapy, Paris, France ; 6 Institut Gustave Roussy, radiotherapy, Villejuif, France Purpose or Objective Although large volumes of information are entered on a daily basis into our electronic medical records, radiation oncology record and verify system and treatment planning systems the use of these Big Data is limited. To meet this goal we herein propose a multicenter data farming strategy structuring routine practice processes to improve availability and accuracy of key data elements for automated, electronic extraction to assess clinical outcomes in real life patients. The purpose of this study was to report real life rates and severities of acute radiation-related toxicities across centers in patients who received moderate hypofractionated (HF) versus normofractionated (NF) whole breast irradiation. Material and Methods

Conclusion These results suggest that moderate hypofractionated whole breast irradiation has acceptable acute toxicities, even lower than with normofractionation, in real life unselected breast cancer patients. This results compare favorably with available randomized trial data. Continued follow-up on a national basis is planned to assess late toxicities and oncological outcomes and monitor daily