ESTRO 2020 Abstract Book

S100 ESTRO 2020

should be implemented in routine clinical practice for locally advanced stage NSCLC patients. OC-0200 Heart dose constraints do not predict for cardiac death in radiotherapy for lung cancer K. Banfill 1 , A. McWilliam 1 , A. Abravan 1 , F. Sun 2 , K. Franks 2 , M. Van Herk 1 , C. Faivre-Finn 1 1 University of Manchester, Division of Cancer Sciences, Manchester, United Kingdom ; 2 Leeds Cancer Centre, Clinical Oncology, Leeds, United Kingdom Purpose or Objective Following the results of RTOG 0617, there have been a number of studies investigating the relationship between heart dose and survival in patients undergoing RT for lung cancer. Few of these studies record data on cause of death. The aim of this study is to investigate the ability of conventional heart dosimetric parameters to predict death due to cardiac causes using data from the UK national Data on cancer diagnosis, treatment and cause of death following radical lung cancer RT were obtained from Public Health England for all patients treated at a UK cancer centre between 1/1/10 and 31/12/16. Ethical approval to use patient information was granted by NHS Health Research Authority. Individuals with metastatic disease at time of RT, those who received multiple courses of thoracic RT or concurrent chemoradiotherapy where excluded. All patients who received > 45Gy in 20 – 25 fractions were included. Cardiac cause of death was defined as the following death certificate ICD-10 codes: I11; I13; I20-I25; I30-I52; I70-I71. Death certificates were available for patients who died prior to November 2017, therefore follow-up was censored at this date. Heart dose parameters were extracted from the radiotherapy planning data for patients with a heart contour; V5Gy, V30Gy and mean heart dose (MHD) were calculated (extracted from a whole heart segmentation). Cumulative incidence of death due to cardiac and non-cardiac causes were plotted for all heart dose parameters split on the median. Multi-variable Fine and Gray competing risk analysis was used to model predictors for cardiac death with non-cardiac death as a competing risk. Results Conventional heart dose constraints (MHD, V5Gy and V30Gy) were available for 928 individuals. After censoring at November 2017, 665 individuals had died; 105 with a cardiac cause (11%). Clinical characteristics are shown in Table 1 for patients who died from a cardiac or non-cardiac cause. The median age at time of radiotherapy was 73 years. There was no difference in the cumulative incidence of death due to cardiac or non-cardiac causes in patients with MHD or heart V5Gy above or below the median (Fig. 1). Heart V30Gy >15% was associated with an increased incidence of non-cardiac death (p=0.01) but not cardiac death (p=0.4). This could be explained by the impact of dose on circulating lymphocytes. On Fine and Gray competing risk analysis, correcting for age, sex, PS, smoking status, stage and mean lung dose, no heart dose parameters predicted for cardiac death. However, male sex (p=0.02) and PS≥2 (p=0.003) were associated with a higher risk of death due to a cardiac cause. cause of death registry. Material and Methods

Conclusion Conventional whole heart dose constraints do not predict for death due to cardiac causes following radical lung RT. This may be due to under-reporting of cardiac death in registry data, or could show that dose to the whole heart is a poor surrogate for dose to relevant cardiac substructures. OC-0201 Hodgkin Lymphoma patients treated with IMRT: from dosimetric analysis to cardiovascular disease risk E. Orlandi 1 , V. De Luca 1 , E. Gallio 2 , S. Bartoncini 1 , G.C. Iorio 1 , R. Parise 1 , C. Cavallin 1 , C. Palladino 1 , C. Fiandra 2 , M. Levis 1 , U. Ricardi 1 1 Ospedale Molinette University of Turin, Department of Oncology- Radiation Oncology- Turin, Torino, Italy ; 2 Ospedale Molinette University of Turin, Department of Medical Imaging- Medical Physics- AOU, Torino, Italy