ESTRO 2020 Abstract book

S111 ESTRO 2020

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.

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 Purpose or Objective A brief chemotherapy (CT) followed by radiation therapy (RT) is routinely used in the treatment of Hodgkin Lymphoma (HL), and is the standard of care for early stages. Given the high success rate of these treatments, with 80-90% of patients surviving many decades after getting cured, reduction of late complication - second cancer and cardiovascular diseases (CAD) - is of pivotal relevance. Historically, the cardiovascular risk of patients receiving mediastinal RT is roughly 5-fold increased. To reduce such a relevant risk, high dose gradient techniques like intensity modulated radiotherapy (IMRT) or volumetric modulated arc therapy (VMAT) are increasingly used in the daily routine. Moreover, the application of Involved Site RT (ISRT) and Involved Node RT (INRT) contouring principles allows to irradiate progressively smaller volumes. These strategies reduce the radiation doses received by the organs at risk (OARs) located in the close proximity of the target, which may translate in a decrease of long term treatment complications. In our study, we evaluated the risk of CAD in a large cohort of HL patients that received a course of mediastinal radiotherapy planned with the application of modern contouring and

delivery techniques. Material and Methods