115P Heart and pulmonary artery radiation doses in non-small cell lung cancer

Abstract

Background: Heart and pulmonary artery (PA) radiation doses following radical (chemo) radiotherapy to non-small cell lung cancer (NSCLC) correlate with overall survival (OS). We aimed to quantify radiation doses delivered to heart and PA during radical (chemo) radiotherapy in NSCLC, and to analyse dose volume histogram (DVH) based parameters that were associated with poor OS. Methods: NSCLC patients who underwent radical (chemo) radiotherapy using 3-D conformal radiotherapy between 2015 and 2017 were identified from our institutional radiotherapy electronic database. Heart and PA were contoured according to the Radiotherapy Oncology Group Trial 1106 contouring atlas. Maximum, minimum and mean radiation doses delivered to heart and PA were quantified. DVH based parameters, volume of heart received 5 Gy (V5), and volume of PA received 40, 45, 50, 55 and 60 Gy (V40, V45, V50, V55 and V60 respectively) were obtained from radiotherapy plans and compared with values that showed correlation with poor OS in NSCLC. Results: Out of a total of nineteen patients, 63% had stage III tumours. Twelve patients were treated with 60 Gy/30 (over 6 weeks) and seven were treated with 55 Gy/20 (over 4 weeks) radiation dose-fractionation schedules. For heart, average radiation doses of mean, minimum and maximum radiation doses were 7.49, 0.33 and 44.18 Gy and corresponding PA radiation doses were 27.14, 5.37 and 52.67 Gy. Evidence suggests mean radiation dose of heart >7.8 Gy and heart V5 of >72.3% correlate with poor OS. In our study, we observed mean heart dose and V5 were less than these values in 74% and 89% patients respectively. PA DVH based parameters, V40 ≥ 80%, V45 > 70%, V50 ≥ 45%, V55 ≥ 32% and V60 > 37 correlates with poor OS. In our cohort of patients, V40, V45, V50, V55 and V60 were less than these values in 95%, 89%, 79%, 74% and 89% patients. Conclusions: In this retrospective study, we found heart and PA DVH based radiation dose parameters in NSCLC radical (chemo) radiotherapy were less than those of published values that were associated with poor OS. It is possible to achieve this in 3-D conformal radiotherapy planning for most patients. Including these DVH based parameters during radiotherapy planning would ensure radiation doses to these critical organs are optimised. Legal entity responsible for the study: N/A Funding: Has not received any funding Disclosure: All authors have declared no conflicts of interest.