Prognostic Significance of the Post-Treatment Neutrophil-to-Lymphocyte Ratio in Pharyngeal Cancers Treated with Concurrent Chemoradiotherapy

Background: Even though the pre-treatment neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are well-established prognosticators in various cancers including head and neck cancers, there have been relatively few studies on the clinical significance of the post-treatment values. This study aimed to investigate the changes in NLR and PLR after concurrent chemoradiotherapy (CCRT) and to evaluate their prognostic significance in pharyngeal cancers. Methods: This study was retrospectively conducted on 461 consecutive patients with primary pharyngeal cancer who had received definitive CCRT. Blood test results before and after CCRT were obtained, and the pre- and post-treatment NLR and PLR were calculated. Patient prognosis was evaluated based on overall survival (OS) and relapse-free survival (RFS). Results: After CCRT, the NLR increased from 2.01 (interquartile range (IQR), 1.53–2.62) to 2.69 (IQR, 1.93–3.81), and the PLR increased from 118.84 (IQR, 92.61–151.63) to 193.19 (IQR, 146.28–262.46). Along with high pre-treatment NLR and high pre-treatment PLR, high post-treatment NLR was also significantly associated with worse OS and RFS (p = 0.013 and p = 0.026). In addition, patients with a high ΔNLR (i.e., the difference between pre- and post-treatment NLRs) had significantly worse OS and RFS (p = 0.013 and p = 0.026). However, only a high pre-treatment NLR (hazard ratio (HR), 2.19; 95% confidence interval (CI), 1.17–4.08; p = 0.014), age (HR, 2.16; 95% CI, 1.14–4.08; p = 0.018), and stage IV (HR, 2.11; 95% CI, 1.15–3.89; p = 0.017) were independent prognostic factors for OS in the multivariate analysis. Conclusions: In patients with pharyngeal cancers, following CCRT, the NLR and PLR increased significantly from pre-treatment values. Like the pre-treatment NLR and PLR, a high post-treatment NLR and a significant increase in NLR were also associated with poor prognosis. Further prospective studies are required to prove the independent significance of the post-treatment NLR and PLR.