Plasma D-dimer value as a predictor of malignant lymph node involvement in operable non-small cell lung cancer

Fibrin deposition and remodelling of the extracellular matrix are important early steps in tumour metastasis. The D-dimer value is an indicator of intravascular fibrin formation and degradation. Thus, the D-dimer value may be a predictor of the malignant involvement of lymph nodes in operable non-small cell lung cancer (NSCLC) patients. The study comprised 142 highly suspected lung cancer patients scheduled to undergo pneumonectomy, lobectomy or wedge resection. Of the 142 patients, 124 were subsequently diagnosed as NSCLC, and 18 were subsequently diagnosed as benign lung disease by histological examination. Preoperative plasma D-dimer values were quantified, and the relationship between plasma D-dimer and clinical variables including tumour size, involvement of lymph nodes and clinical stage was examined using Spearman correlation coefficients and χ ² tests. The median plasma D-dimer values were statistically higher in NSCLC patients with malignant lymph nodes than in those who suffered either benign lung disease or carcinoma in situ (Kruskal–Wallis test; P = 0.001). Plasma D-dimer values were significantly correlated with clinical stage (ANOVA; P = 0.009). An obvious relationship was observed between elevated D-dimer (>0.475 mg/L fibrinogen equivalent units) and malignant lymph node involvement (χ ² test; P = 0.0000). This correlation suggests that the plasma D-dimer value is a clinically important predictor for the malignant involvement of lymph nodes in operable NSCLC.