Prognostic significance of dynamic changes in lymphocyte-to-monocyte ratio in patients with head and neck cancer treated with radiotherapy: results from a large cohort study

Background and purpose: We sought to investigate whether dynamic changes in lymphocyte-to-monocyte ratio (LMR) occurring during the course of radiotherapy (RT) may have prognostic value in patients with head and neck cancer (HNC). Materials and methods: We retrospectively reviewed the clinical records of patients with HNC who underwent RT at our center between 2005 and 2013. Generalized estimating equations were used to longitudinally assess changes in LMR through the course of RT. Delta-LMR was calculated as the difference between LMR measured during treatment and baseline LMR values. Freedom from metastasis (FFM) and overall survival (OS) served as the main outcome measures. Results: A total of 1431 patients with HNC were enrolled. After a median follow-up of 9 years, 636 (44.4%) patients died and 240 (16.8%) had distant metastases. Compared with patients with low delta-LMR at two weeks, those with high delta-LMR experienced less favorable outcomes (five-year OS: 73% versus 59%, respectively, p < 0.001; five-year FFM: 87% versus 80%, respectively, p = 0.015). Similar findings were observed for delta-LMR measured at four weeks (five-year OS: 72% versus 60%, p < 0.001; five-year FFM: 86% versus 79%, respectively, p = 0.002) and six weeks (five-year OS: 72% versus 57%, p < 0.001; five-year FFM: 87% versus 79%, respectively, p = 0.002). Multivariate analysis identified delta-LMR as an independent prognostic factor for both FFM and OS. Conclusion: Delta-LMR is a simple and inexpensive biomarker that may be clinically useful for predicting FFM and OS in patients with HNC treated with RT.