Impact of heart and lung dose on early survival in patients with non-small cell lung cancer treated with chemoradiationDosimetric factors and survival in lung cancer

Background and purpose To determine whether the impact of heart dose on early overall survival (OS) reported in RTOG 0617 could be confirmed in an independent cohort. Materials and methods Heart and lung dose-volume histogram data were retrospectively extracted for patients with stage IIIA-IIIB non-small cell lung cancer (NSCLC) who had received radiotherapy using 3D CRT, IMRT or proton therapy delivered with concurrent chemotherapy between 1999 and 2010. Potential associations between clinical and dosimetric factors and OS up to 24 months after start of treatment were assessed in univariate and multivariate analyses with log-rank tests or Cox proportional hazards models. Results 468 patients met inclusion criteria. Factors associated with increased risk of early death in univariate analyses were performance status (PS), stage, treatment with 3D conformal radiotherapy, lower tumor dose and larger gross tumor volume (GTV), mean heart dose (MHD), heart V5, mean lung dose (MLD) and lung V5. Factors retaining significance in multivariate analysis were PS, GTV, and MLD. There was a strong correlation between MHD and heart V5 with MLD. However, no evidence was found that heart doses had an independent effect on OS during the first 2 years. Conclusions In a large group of patients treated with chemoradiation for locally advanced NSCLC, heart dose was not found to be associated with early survival outcomes when lung dose was taken into account. Nevertheless, based on the known adverse effects of radiotherapy on vasculature and cardiac function, dose to the heart should be minimized during radiotherapy planning.