Lymphocyte-Monocyte Ratio Significantly Predicts Recurrence in Papillary Thyroid Cancer

A growing body of evidences shows that systemic inflammatory responses are involved in patient prognosis in multiple cancers. Combinations of peripheral leukocyte fractions have been shown to be useful markers for the inflammatory responses. However, significance of such systemic inflammatory responses is still unknown in thyroid cancer. Accordingly, we aimed to clarify clinical impact of peripheral leukocyte fractions in papillary thyroid cancer (PTC).

Clinicopathological analyses were performed including preoperative leukocyte fractions in 570 patients with curatively resected PTC. Receiver operating characteristic curves were used to determine cutoffs of leukocyte fraction or inflammation indexes such as lymphocyte-to-monocyte ratio (LMR) and neutrophil-to-lymphocyte ratio. A Kaplan-Meier analysis and a Cox's proportional hazard model were used to conduct prognostic analysis. A multivariable logistic regression analysis was performed for correlation assay.

Preoperative low LMR predicted recurrence with high sensitivity (63.3%) and specificity (68.7%) (P = 0.002). The multivariable prognostic analyses revealed that preoperative low LMR (P = 0.025), pathological N1b (P = 0.019), high metastatic lymph node ratio (node density) (P = 0.014), and high thyroglobulin level (P = 0.002) independently predicted worse prognosis. The combination of these independent parameters clearly enriched high-risk patients (P < 0.001). Of note, low LMR was dramatically associated with recurrence especially in patients with advanced PTC.

Preoperative low LMR dramatically predicts high-risk patients for recurrences. The results in this study give rational to focusing on immune cell profiles to tackle advanced PTC.