Neutrophil-lymphocyte ratio dynamics associated with survival after SBRT for stage I-II lung cancer
PO-1451
Abstract
Neutrophil-lymphocyte ratio dynamics associated with survival after SBRT for stage I-II lung cancer
Authors: Sahar Shahamatdar1, Kevin King2, Soumyajit Roy2, Mara Batus2, Mary Jo Fidler3, Philip Bonomi3, Gaurav Marwaha2, Mudit Chowdhary1
1Warren Alpert Medical School of Brown University, Department of Radiation Oncology, Providence, USA; 2Rush University Medical Center, Department of Radiation Oncology, Chicago, USA; 3Rush University Medical Center, Department of Hematology, Oncology, and Cell Therapy, Chicago, USA
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Purpose or Objective
Neutrophil-to-lymphocyte ratio (NLR) is a surrogate for systemic inflammation and the tumor microenvironment. Recently, pre-treatment NLR has been shown to be a prognostic factor in various malignancies. Stereotactic body radiotherapy (SBRT) has been linked to systemic antitumor T-cell response via immune stimulation. Therefore, we investigated the prognostic value of percent (%) change in NLR before and after SBRT in early-stage lung cancer.
Material and Methods
Patients treated with SBRT for stage I-II lung cancer from 2012-2020 were retrospectively identified. Pre-, post- treatment and % change in NLR were calculated from full blood counts obtained in closest proximity to SBRT. Patients were divided into two cohorts based on % change in NLR; receiver operator curve analysis was used to find the optimal cut point for % change in NLR. Overall survival (OS) was estimated by the Kaplan-Meier (KM) method. Intra- and extra-thoracic outcomes were calculated using the cumulative incidence model with competing risk for death. Univariate and multivariate Cox proportional hazards analyses were performed to identify the association of % change in NLR with OS, intra-&extra-thoracic outcomes. The models were adjusted for confounding variables.
Results
102 patients had full blood counts pre and post SBRT. The optimal cut point for NLR change with respect to OS was a 54.2% increase. Key baseline characteristics (ie stage, age, smoking, SBRT dose, fractions, BED) were well balanced across the cohorts, except for sex. Patients with % change in NLR >54.2% had significantly worse OS (2-yr: 79.2% vs 41.7%) and distant recurrence (2-yr: 18.3% vs 38.5%). % change in NLR was a significant predictor for worse OS (HR 2.58, 95%CI 1.24-5.37, p<0.05) and distant recurrence (HR 3.01, 95%CI 1.18-8.08, p<0.05) on multivariate analysis. There were no significant associations of change in NLR with lobar, local, or nodal recurrence.
Conclusion
Percent increase in NLR following SBRT is associated with higher distance recurrence and worse survival in patients with early-stage lung cancer. If prospectively validated, NLR could be a cost-effective marker to identify high-risk patients who may benefit from closer surveillance and possibly even treatment escalation.