Original Article

Heart V5 predicts cardiac events in unresectable lung cancer patients undergoing chemoradiation

Lisa Ni, Matthew Koshy, Philip Connell, Sean Pitroda, Daniel W. Golden, Hania Al-Hallaq, Greg Hubert, Greg Kauffman, Anne McCall, Renuka Malik


Background: Recent studies incorporating dose escalated radiation identified heart dose as a predictor of cardiac toxicity in unresectable lung cancer patients. Whether conventionally dosed radiation impacts cardiac events remains unclear.
Methods: Stage III lung cancer patients undergoing definitive chemoradiation to 60–70 Gy were analyzed. Clinical and dosimetric factors (mean heart dose, heart V5-60 in 5 Gy increments) were analyzed against freedom from ≥ grade 3 cardiac events and overall survival (OS) by log-rank test. Multivariable analysis (MVA) for factors significant on univariate analysis was performed by Cox proportional hazards.
Results: A total of 108 patients were identified. Median follow-up was 18.0 months. One- and two-year OS were 79% and 61%, respectively. On MVA, gross tumor volume (GTV) ≥98.6 cm3 [hazard ratio (HR): 2.11, 95% confidence interval (CI): 1.15–3.93, P=0.02] and female gender (HR: 2.01, 95% CI: 1.09–3.73, P=0.03) predicted for worse survival. Twelve patients (11%) developed ≥ grade 3 cardiac events. One- and two-year freedom from cardiac events (FFCE) was 94% and 84% respectively. On MVA, heart V5 ≥49% predicted for cardiac events (HR: 11.44, 95% CI: 1.31–111.60, P=0.03) while female gender was nearly significant (HR: 3.49, 95% CI: 0.97–16.80, P=0.06). Females presented with similar comorbidity scores, GTVs, and relapse rates but experienced higher heart doses than their male counterparts.
Conclusions: Heart V5 ≥49% predicted for cardiac events after chemoradiation. However, cardiac dosimetry was not associated with survival. Rather, female gender and GTV ≥98.6 cm3 led to worse survival. This study corroborates emerging data that low-dose radiation to the heart impacts cardiac toxicity.

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