ESTRO 2021 Abstract Book

S1683

ESTRO 2021

1 Hospital Universitari Sant Joan de Reus, Radiation Oncology Department, Reus, Spain; 2 Klinik im Hasel, Lucerne, Klinik im Hasel, Lucerne, Reus, Spain; 3 Hospital Universitari Sant Joan de Reus,, Radiation Oncology Department, Reus, Spain; 4 7LMU Klinik und Poliklinik für Strahlentherapie und Radioonkologie, Radiation Oncology Department, Munich, Germany Purpose or Objective Breast reconstruction rates are increasing in breast cancer (BC) patients having postmastectomy radiation therapy (PMRT) in recent years, due to the cosmetic results. The main objective of this study is to evaluate the late toxicity in women with breast reconstruction in two European hospitals of Germany and Spain. Materials and Methods All patients diagnosed of BC with PRMT in an retrospective analysis, with total irradiation of the thoracic wall +/- regional lymph nodes +/- boost. The mein variables of the analysis were reconstruction type, reconstruction time, radiotherapy technique (3D, VMAT, Deep inspiration breath hold (DIBH)), total dose and late chronic toxicity. Acute and late toxicities were calculated according to the RTOG criteria to classify the degree of fibrosis and radiodermatitis. The following algorithm was used for the partial defects of reconstructed breasts, classified into one of three types Type I (good cosmetic result), Type II (regular cosmetic result) and Type III (bad cosmetic result). All statistical calculations and graph representations were performed with the statistical package for social sciences (SPSS 22.0) Results Between November 2014 and 2020, were included 83 women (57 from Germany and 26 from Spain) with a mean follow-up period of 22 months (range, 3-89 months). Patient characteristics are summarized in table 1. Twenty eight (28%) patients experimented late toxicity, fibrosis type. Presented toxicite grade 1 (23.68%) and toxicite grade 2 (5.26%). Figure 1 and 2. Presented cosmetic respectively to type I (62.5%), typ II (31.33%), type III (6.02%). Figure 3. The type of reconstruction, the time of reconstruction, time fron surgery to start of radiotherapy and the radiotherapy technique was not statistically related with fibrosis, repsectively (p=0.71), (p= 0.55), (p=0.53) and (p=0.70).

Conclusion PMRT has shown acceptable late toxicity, fibrosis type. It was also evidenced excellent cosmetic results for both populations. No significant association was observed with respect to fibrosis and the type of reconstruction, reconstruction time, time fron surgery to start of radiotherapy or radiotherapy technique. PO-1979 The association between radiotherapy doses to bone marrow and fatigue in prostate cancer A. Alshamrani 1 , M. Aznar 2 , B. Rowland 3 , P. Hoskin 4 , A. Choudhury 4 , C. Eccles 2 1 The University of Manchester, Faculty of Biology, Medicine and Health , Manchester, United Kingdom; 2 The University of Manchester, Division of Cancer Sciences, Manchester, United Kingdom; 3 The University of Manchester, Division of Molecular & Clinical Cancer Studies, Manchester, United Kingdom; 4 The Christie NHS Foundation Trust, Department of Clinical Oncology, Manchester, United Kingdom Purpose or Objective Bone Marrow (BM) is the primary site of haematopoiesis and, in prostate radiotherapy, 50%–55% of active BM is found in the treatment volume. Recent studies showed a robust association between Integral Dose (ID) and increased levels of fatigue in prostate cancer (PC) patients. Although these results require further validation, from a clinical perspective, the critical structure is thought to be the BM. We have investigated the BM dose compared to the ID as a predictor of patient-reported