High Neutrophil Count as a Negative Prognostic Factor for Relapse in Patients with Thymic Epithelial Tumor

Preoperative neutrophil count is reportedly associated with poor prognosis in cancer patients. This study aimed to investigate the clinical significance of pre-treatment peripheral blood cell counts in patients with thymic epithelial tumors (TETs).

A retrospective review of 71 patients with completely resected TETs [64 thymoma, 6 thymic carcinoma, and 1 thymic neuroendocrine tumor] between 2000 and 2018 was conducted. Associations between tumor recurrence and pre-treatment peripheral blood cell counts of leukocytes (WBC), neutrophils (Neut), lymphocytes (Lymph), monocytes (Mono), and platelets (Plt) were analyzed. Optimal cut-off points were selected using receiver operating characteristic curve analysis to predict tumor recurrence.

High WBC (≥ 7000), Neut (≥ 4450), and Plt (≥ 226 × 10³) counts had significantly poor relapse-free survival (RFS), but high Lymph (≥ 1950) and Mono (≥ 400) did not. High Neut had the strongest correlation with recurrence (area under curve, 0.800); we focused on the analysis between high-Neut and low-Neut groups. High Neut count significantly correlated with smoking history, pre-treatment C-reactive protein level, and advanced stage; high Neut count and aggressive histology tended to show correlations. RFS was significantly poorer in the high-Neut group than in the low-Neut group (p = 0.003), with 5-year RFS rates of 63.8% and 96.8%, respectively. High Neut count was a significant adverse predictor for RFS and cumulative incidence of recurrence (p = 0.005 and p < 0.001, respectively). The risk scoring system comprising high Neut count, advanced stage, and aggressive histology demonstrated better prognostic ability than any prognostic factors alone.

High Neut count significantly correlated with TET recurrence, suggesting a negative prognostic effect of latent inflammation in TET patients.