Cardiac toxicity from radical radiotherapy for lung cancer

Introduction Lung cancer is the leading cause of cancer mortality worldwide. Radical radiotherapy is the standard non-surgical management of non-metastatic lung cancer. Cardiac toxicity has been associated with worse survival outcomes following lung cancer radiotherapy. This research project aims to discover clinical and radiotherapy dosimetric factors associated with radiotherapy-induced cardiac damage in lung cancer. Methods The research project consist of two phases. Phase one involves retrospective analysis of clinical, tumour and radiotherapy dosimetric data in a cohort of patients treated with radical radiotherapy at the Leeds Cancer Centre from 2010 to 2016. Additional national data was requested from Public Health England. Cause of death from cardiac causes and cancer causes were analysed, and compared in patients who died at home and at the hospital. Medical comorbidities, including pre-existing cardiac disease, diabetes, COPD and kidney failure are analysed for their association with overall survival and post radiotherapy cardiac events. Phase two is a prospective cohort study. This involves testing cardiac biomarkers in 100 patients who are undergoing radical lung cancer radiotherapy at the Leeds Cancer Centre, and correlating the results with clinical and dosimetric variables. These form part of a multi-centre study funded by Yorkshire Cancer Research. Results Pre-existing cardiovascular conditions comprise in excess of 30% of this study population. Dosimetric analysis of radiotherapy plans reveal different dose regions associated with cardiovascular death, in patients with or without pre-existing heart disease. Cardiac death is likely to be under reported, particularly in the community. Medical comorbidities, in particular COPD and chronic kidney disease, affect post radiotherapy survival and can influence onset of post radiotherapy cardiac events. The prospective biomarker study has been set up in Manchester and Leeds, and is currently recruiting. Conclusion Cardiac toxicity from lung cancer radiotherapy occurs due to complex interactions between demographic, medical and radiotherapy factors. Further work involving prospective studies, cardiac biomarkers and novel imaging techniques will help to further elucidate the mechanisms of cardiac damage, and strategies to minimise it.