Dosimetric Correlate of Cardiac-Specific Survival Among Patients Undergoing Coronary Artery Stenting After Thoracic Radiotherapy for Cancer
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 cm3 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.