Chest radiation increases cardiac risk in NSCLC patients
medwireNews: Patients with locally advanced non-small-cell lung cancer (NSCLC) have a high risk for major adverse cardiac events (MACE) after radiotherapy that may warrant a reduction in cardiac radiation dose, study findings indicate.
Raymond Mak (Dana-Farber Cancer Institute and Brigham and Women's Hospital, Boston, Massachusetts, USA) and co-investigators say that their results “highlight the importance of early recognition and treatment of cardiovascular events” in patients with NSCLC.
During a median follow-up period of 20.4 months, 10.3% of 748 patients with locally advanced NSCLC who were treated with thoracic radiotherapy developed at least one MACE (cardiac death, unstable angina, myocardial infarction, hospitalization for heart failure, and coronary revascularization) and 71.3% died.
After adjustment for potential lung cancer and cardiovascular confounders, including preexisting coronary heart disease (CHD), the researchers found that each 1-Gy increase in mean radiation dose delivered to the heart was associated with a significant 5% increased risk for MACE and a significant 2% increased risk for all-cause mortality.
In addition, there was a significant interaction between mean heart dose and CHD.
Specifically, treatment at a mean heart dose of 10 Gy or higher was associated with a significant three-fold greater risk for MACE relative to a lower dose in the 480 patients without preexisting CHD, with estimated 2-year cumulative incidences of 3.5% versus 1.1%.
Mak and co-authors point out in the Journal of the American College of Cardiology that these rates exceed those observed in Framingham Heart Study participants and “surpass guideline thresholds for recommending aggressive risk reduction.”
By contrast, there was no significant interaction with dose among the 268 patients with CHD. In this group, the estimated 2-year cumulative incidence of MACE was 12.1% among the patients who received a mean heart dose of 10 Gy or higher and 10.0% among those who received a lower dose.
A similar pattern was seen for all-cause mortality, with CHD-negative patients having a significant 1.34-fold higher risk for death when they received a mean heart dose of at least 10 Gy versus a lower dose (2-year incidence of 52.2 vs 40.0%), whereas CHD-positive patients had no dose-dependent increased risk for death (2-year incidence of 54.6 vs 50.8%).
Mak and team also analyzed the data for adverse events (AEs) and found that, after adjustment for baseline CHD or arrhythmia and treatment regimen, each 1-Gy increase in mean heart dose was associated with a 3% increase in the risk for grade 3 or higher AEs, with a trend toward an interaction between dose and CHD similar to that seen for MACE and all-cause mortality.
The researchers conclude: “Despite the competing risks of cancer-related death, patients with locally-advanced non–small cell lung cancer may benefit from reduction of cardiac radiation dose, preventive post-radiotherapy cardiac care, and earlier recognition and treatment of cardiovascular events.”
They add: “Prospective studies are needed to assess the effect of combined cardiac risk stratification, cardiac radiation dose reduction techniques, and post-radiotherapy preventive care on survival and quality of life in patients with lung cancer.”
By Laura Cowen
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