Dosimetric Correlate of Cardiac-Specific Survival among Patients Undergoing Coronary Artery Stenting after Thoracic Radiotherapy for Cancer

Objectives: To retrospectively evaluate outcomes among cancer survivors previously treated with thoracic radiotherapy (RT) who later underwent percutaneous coronary intervention (PCI). Methods: From 1998 to 2012, 76 patients first received curative RT (>30 Gy, except for Hodgkin lymphoma patients) involving the heart and lungs followed by PCI. Heart and lung-specific dosimetric parameters were correlated with overall survival (OS) and cardiac-specific survival by Cox variate methods. Results: The mean interval between cancer diagnosis and PCI was 3.7 years (range, 0.1 to 12.6 y). Median follow-up since cancer diagnosis was 5.5 years. At analysis, 46 patients (61%) were alive, 5 (7%) died of cardiac causes, and 9 (12%) of cancer. Higher maximum RT heart dose was related to poorer OS since PCI (P=0.009). Angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (P=0.005) and higher mean heart dose (P<0.001) were related to poorer OS since cancer diagnosis. β-Blockers, higher mean heart dose (hazard ratio [HR]=1.49, P<0.001), and percentage of targeted volume or organ receiving ≥40 Gy for heart doses (HR=1.32, P<0.001) were associated with poorer non-cancer-specific survival since cancer diagnosis. Diabetes (HR=3.84, P=0.008) and increased percentage of targeted volume or organ receiving ≥45 Gy (HR=1.01 per additional 100 cm 3 irradiated, P=0.01) for the heart decreased major adverse cardiac event-free survival. Conclusions: Prior heart and lung-directed RT had volume-dependent and dose-dependent adverse effects on long-term cardiac outcomes for patients subsequently treated with PCI. RT planning that minimizes heart and lung irradiation doses should be encouraged.