Blood Lymphocytes as a Prognostic Factor for Stage III Non-small Cell Lung Cancer with Concurrent Chemoradiation

In this study, we aimed to identify blood lymphocytes as a prognostic factor for survival in patients with locally advanced stage III non-small cell lung cancer (NSCLC) treated with concurrent chemoradiotherapy (CCRT). We conducted a secondary analysis of 196 patients enrolled in the Korean Radiation Oncology Group 0903 phase III clinical trial to evaluate the prognostic significance of circulating blood lymphocyte levels. The median total lymphocyte count (TLC) reduction ratio during CCRT was 0.74 (range: 0.29 – 0.97). In multivariate analysis, patient age (p = 0.014) and gross tumor volume (GTV, p = 0.031) were significant factors associated with overall survival, while TLC reduction (p = 0.018) and pretreatment neutrophil-to-lymphocyte ratio (NLR; p = 0.010) were associated with progression-free survival (PFS). In multivariate logistic regression analysis, pretreatment NLR, GTV, and heart V20 were significantly associated with TLC reduction. TLC reduction during CCRT is a significant prognostic factor for PFS, and heart V20 is significantly associated with TLC reduction. Thus, constraining the volume of the radiation dose to the whole heart must be prioritized to reduce TLC.