ESTRO 2021 Abstract Book

S153

ESTRO 2021

1 IEO, European Institute of Oncology, IRCCS, Radiation Oncology, Milan, Italy; 2 IEO, European Institute of Oncology, IRCCS, Medical Physics, Milan, Italy; 3 IEO, European Institute of Oncology, IRCCS, Breast Surgery, Milan, Italy; 4 University of Milan, Oncology and Hemato-oncology, Milan, Italy; 5 IEO, European Institute of Oncology, IRCCS, Scientific Directorate, Milan, Italy Purpose or Objective To evaluate the efficacy and tolerance of intraoperative electron boost (IOERT) followed by hypofractionated whole breast irradiation (WBI) for early breast cancer (BC). Materials and Methods P remenopausal women with pT1-2 any N BC operated on with breast conserving surgery received 12 Gy intraoperative boost with electrons (IOERT) to the tumor bed via mobile dedicated linear accelerator and hypofractionated schedule to whole breast with 3- dimensional conformal radiotherapy (WBI) and 6-MV photon. The WBI schedule consisted of 13 fractions of 2.85 Gy over 2.5 weeks. Patients were analyzed to assess local control, disease free survival (DFS), breast cancer specific survival (BCSS) and overall (OS). Results From 6/2004 to 12/2014 518 consecutive BC patients with a median age of 43 (range, 24-48) were identified. Very young patients, <40 were 163. Median tumor size was 1.5 cm (standard deviation-SD, 0.70). Nodal negative patients were 356. According to molecular classification, 42% were Luminal A, 31.5% Luminal B HER2 negative, 11.4% Luminal B HER2 positive, 2.3% HER2 positive, and 13% Triple Negative. Median IOERT collimator size was 4 cm (range, 4-6) and median electron energy was 7 MeV ( range 5-10). Perioperative complications, of which clinical liponecrosis accounted for 3.5%, affected 16.4% of the population. After mean interval of 25 days (SD, 7), hypofractionated WBI was delivered. All patients completed RT as scheduled and the mean duration of RT was 18. In about 10% the 13-fraction RT lasted more than 20 days. In all but a few cases, chemotherapy, if delivered, started at the end of RT. Median follow-up was 118 months (range, 9-182 months). Five-year and 10-year cumulative incidence of local relapses was 1.5% (95% CI, 0.7-2.9) and 3.4% (95%CI, 2.0-5.3), respectively. Patients aged <40 had significantly higher local recurrence rate (at 10 years 5.2 vs 2.5%, p 0.045). At multivariate analysis, predictors for local failure were aged <40, presence of intraductal component (EIC) and smaller IOERT collimator. Ten-year survival outcomes were as follows: DFS 78.1% (95% CI, 74.0-81.7), BCSS 96.4% (95% CI, 94.3-97.8%), OS 95.5% (95% CI, 93.2-97.1). No difference between women aged <40 and ≥40 was observed, while Luminal B HER2 negative showed the worst outcome. Distant metastases occurred in 8.1%, especially in the Luminal B HER2 negative tumors. Moderate/severe fibrosis was reported in about 40% of the cases and moderate/severe pain in 12% of the cases. Radiological liponecrosis was found in 65% of the imaging studies (data not available for 155/518). Patients who experienced clinical liponecrosis were more likely to report higher chronic toxicity. Cosmesis was scored as excellent/good in 85% of the cases. Conclusion After 10 years, IOERT boost and hypofractionated WBI resulted to be effective, with some concerns regarding the rate of tumor bed fibrosis. PH-0220 Long-term quality of life in breast cancer survivors 10 years after radiotherapy P. Seibold 1 , Y. Gao 1 , S. Behrens 1 , J. Chang-Claude 1,2 1 German Cancer Research Center (DKFZ), Division of Cancer Epidemiology, Heidelberg, Germany; 2 University Medical Center Hamburg-Eppendorf, Research Group Genetic Cancer Epidemiology, University Cancer Center Hamburg (UCCH), Hamburg, Germany Purpose or Objective With increasing survival rates in breast cancer patients, quality of life (QoL) has become a major focus of outcomes research. Cancer survivors may experience adverse effects of cancer and/or treatment years after treatment such as radiotherapy (RT), which may negatively impact QoL. However, there are few prospective studies evaluating QoL beyond five years post-diagnosis. Therefore, the objectives of this study were: (1) to assess the longitudinal course of QoL in breast cancer survivors treated with RT (breast conserving surgery, no chemotherapy) from treatment to 10 years post-diagnosis; (2) to compare the QoL of long-term breast cancer survivors 10 years post-RT with unaffected women (controls). Materials and Methods 292 breast cancer patients diagnosed 1998-2001 and recruited into an observational study on radiosensitivity were followed up prospectively for a median of 137 months. QoL was scored at baseline (beginning of RT), during RT until 6 weeks after end of RT as well as at the 10-year follow-up using the EORTC QLQ-C30 questionnaire. Time course of QoL was assessed using non-parametric repeated measures ANOVA. QoL in long- term survivors was compared to that of controls also followed-up for 10 years from a previous case-control study conducted in the same region and comparable time period by the Wilcoxon test, stratified by three age In longitudinal analysis, Global Health Status/QoL (GHS/QoL) declined during RT and improved within 6 weeks after RT. Physical functioning was significantly lower at the 10 year follow-up compared to 6 weeks after RT, while role functioning significantly improved between end of RT and the 10 year follow-up. Deficits in most symptoms, including dyspnea, fatigue, insomnia, appetite loss, nausea/vomiting and constipation, worsened from baseline to the earlier stages of RT but then improved 6 weeks after RT. Patients reported significantly more symptoms such as dyspnea (mean 24.7 +/- 3.6 vs. 15.9 +/- 5.0, p<0.001), nausea/vomiting and diarrhea at the 10-year follow-up compared to 6 weeks after RT. In cross-sectional analysis, GHS/QoL reported by long-term breast cancer survivors was comparable to that of the controls (p>0.05). However, across all age-groups, patients reported significantly (p<0.05) lower scores on emotional functioning as well as more symptoms including insomnia and nausea/vomiting compared to age- matched controls. Additionally, patients under 75 years reported significantly lower physical functioning and higher fatigue scores, with larger differences in patients under 65 years (e.g. fatigue: mean 35.0 +/- 7.1 vs. groups. Results