An Increased Neutrophil-to-Lymphocyte Ratio Predicts Incomplete Response to Therapy in Differentiated Thyroid Cancer

Background: Previously we have shown that an elevated baseline neutrophil-to-lymphocyte ratio (NLR) was associated with a high risk of recurrence in patients with differentiated thyroid cancer. The clinical significance of the longitudinal changes in NLR following treatment remained unestablished. Methods: Adults patients with differentiated thyroid cancer were included in the study if the follow-up NLR data at 6 to 18 months after initial treatment were available. The response to treatment was categorized as excellent, indeterminate, biochemical incomplete, and structural incomplete as per guidelines of the American Thyroid Association. Results: Among 151 patients with thyroid cancer, a significant decrease in NLR following treatment was observed in those with stage I disease, those with low risk of recurrence, and those with an excellent response to therapy. Patients with a structural incomplete response had a significant increase in NLR at follow-up (p = 0.012). On multivariate analysis, incomplete response to therapy was associated with male sex (odds ratio [OR] = 3.35), tumor size (OR = 1.63), lymph node metastasis (OR = 4.80), distant metastasis (OR = 12.95), and increased NLR (OR = 13.68). Conclusions: An increase in systemic inflammation following treatment as measured by NLR is independently associated with an incomplete response to therapy in differentiated thyroid cancer.