Radiation Therapy Is Associated With An Increased Incidence Of Cardiac Events In Small-Cell Lung Cancer Patients

Publication date: Available online 6 June 2018
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Matthew J. Ferris, Renjian Jiang, Madhusmita Behera, Suresh S. Ramalingam, Walter J. Curran, Kristin A. Higgins
PurposeCardiac radiation dose was a predictor of inferior overall survival (OS) in the non-small-cell lung cancer trial RTOG 0617. We examined the association between radiation therapy (RT) and cardiac events (CE) for small cell lung cancer (SCLC) patients.Methods and MaterialsThe US population-based Surveillance, Epidemiology, and End Results (SEER) Program and Medicare claims databases were queried for rates of CE among SCLC patients treated with chemotherapy (CTX) +/- RT. Propensity score matching (PSM) and multivariate analysis (MVA) were conducted. Patients were matched for actual/theoretical RT start date (to prevent immortal time bias) and then full PSM balanced clinical characteristics. Cumulative incidence function curves were generated.ResultsFrom 2000 – 2011, 7,060 patients were included: 2,892 limited-stage (LS-SCLC) and 4,168 extensive-stage (ES-SCLC). Grouping LS-SCLC and ES-SCLC together, the incidence of CE for the CTX + RT and CTX-only groups was 44.1 vs. 39.0% at 60 months (P = 0.008). After PSM (5,286 patients), the incidence of CE for the CTX + RT and CTX-only groups was 43.0 vs. 38.6% at 60 months (P = 0.033). Analysis of only LS-SCLC (2,016 patients) demonstrated the incidence of CE for CTX + RT vs. CTX-only groups was 50.3 vs. 42.0% at 60 months (P = 0.0231). MVA again demonstrated association between CE and RT (HR 1.20; 95% CI 1.06 – 1.37; P = 0.005). After PSM (1,614 patients), the incidence of CE for CTX + RT vs. CTX-only groups was 51.7 vs. 41.6% at 60 months (P = 0.0042).ConclusionsSCLC patients are at significant risk of developing CE post-treatment; RT is associated with an absolute increase in the rate of CE at 5-years of approximately 5% for all SCLC patients, and up to 10% for LS-SCLC patients. Cardiac risk management and cardiac-sparing RT techniques should be further evaluated for SCLC patients.

Teaser

Among small-cell lung cancer patients, we found baseline rates of cardiac events are about 40% at 5-years in the US population. Treatment with radiation therapy contributes to an absolute increase in this rate of cardiac events at 5-years of approximately 5% for all patients (limited-stage and extensive-stage both), and up to 10% for the limited-stage population.


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