Association of cardiac calcium burden with overall survival after radiotherapy for non-small cell lung cancer.

ABSTRACT

Background and purpose: Coronary calcifications are associated with coronary artery disease in patients undergoing radiotherapy (RT) for non-small cell lung cancer (NSCLC). We quantified calcifications in the coronary arteries and aorta and investigated their relationship with overall survival (OS) in patients treated with definitive RT (Def-RT) or post-operative RT (PORT). Materials and methods: We analyzed 263 NSCLC patients treated from 2004 to 2017. Calcium burden was ascertained with a Hounsfield unit (HU) cutoff of > 130 in addition to a deep learning (DL) plaque estimator. The HU cutoff volumes were defined for coronary arteries (PlaqueCoro) and coronary arteries and aorta combined (PlaqueCoro+Ao), while the DL estimator ranged from 0 (no plaque) to 3 (high plaque). Patient and treatment characteristics were explored for association with OS. Results: The median PlaqueCoro and PlaqueCoro+Ao was 0.75 cm3 and 0.87 cm3 in the Def-RT group and 0.03 cm3 and 0.52 cm3 in the PORT group. The median DL estimator was 2 in both cohorts. In Def-RT, large PlaqueCoro (HR1.11 (95%CI1.04-1.19); p = 0.008), and PlaqueCoro+Ao (HR1.06 (95%CI1.02-1.11); p = 0.03), and poor Karnofsky Performance Status (HR 0.97 (95%CI 0.94-0.99); p = 0.03) were associated with worse OS. No relationship was identified between the plaque volumes and OS in PORT, or between the DL plaque estimator and OS in either Def-RT or PORT. Conclusions: Coronary artery calcification assessed from RT planning CT scans was significantly associated with OS in patients who underwent Def-RT for NSCLC. This HU thresholding method can be straightforwardly implemented such that the role of calcifications can be further explored.