Lymphocyte-to-monocyte ratio prior to radioiodine ablation in low- and intermediate-risk, papillary thyroid cancer.

Purpose: We aimed to investigate inflammation indices based on preablation hematological parameter of the lymphocyte-to-monocyte ratio (LMR) to predict the clinical outcome in papillary thyroid cancer (PTC) patients with low- and intermediate-risk stratification.

Methods: This retrospective study analyzed 772 patients with low- and intermediate-risk PTC who underwent total thyroidectomy followed by radioiodine therapy between July 2005 and July 2009 with a median of 10 years. Kaplan-Meier statistics were used to test differences in recurrence-free survival (RFS) between groups based on the optimal cutoff point of biomarkers identified using receiver operating characteristic curves.

Results: With an optimal cutoff point of 7.05, 215 patients (29.8%) were classified as having low LMR and 557 patients (71.2%) were classified as having high LMR. High LMR was significantly associated with a prolonged RFS (hazard ratio [HR]: 2.048, 95% confidence interval [CI]: 1.062-4.359, p = 0.001). Multivariate analysis showed that low LMR (HR = 2.035, 95% CI: 1.011-4.095, p = 0.012), tumor size over 2 cm (HR = 2.762, 95% CI: 1.303-5.852, p = 0.008), and high preablative simulated thyroglobulin level over 10 ng/ml (HR = 7.826, 95% CI: 2.353-26.033, p < 0.001) were independent prognostic markers for worse RFS in the enrolled PTC patients.

Conclusions: LMR at the time of radioiodine therapy has comparable predictor for the clinical outcome with both tumor size and preablative simulated thyroglobulin level in low- to intermediate-risk PTC patients.