Three Dimensional Measurement of the Space Distance Between the Hilum and Clinical Stage T₁ Non-small Cell Lung Cancer and Its Relationship with Lymph Node Metastasis

  Objective  The aim of this study was to develop a novel method to quantitatively define the tumor location of clinical stage T₁ (cT₁) non-small cell lung cancer (NSCLC) and to evaluate its impact on lymph node metastasis in a large cohort group.

  Methods  We developed a novel method to transform the datum of 2D CT scans to 3D datum and to quantitatively measure the distance between the tumor and hilum through the Pythagorean theorem. Multiple logistic regression analysis was applied to identify the risk factors associated with lymph node metastasis.

  Results  A total of 399 patients (166 male and 233 female) with cT₁ NSCLC were enrolled in this study. The mean age was (57.48±10.88) yr., the mean distance between tumor and hilum was (5.44±1.96) cm, and the mean tumor diameter was (1.77±0.65) cm. Patients were divided into lymph node positive group (N⁺ group) and lymph node negative group (N^－ group). By multiple logistic regression analysis, we identified 4 risk variables associated with lymph node metastasis. Gender (odds ratio (OR)=2.118, P=0.022), distance between tumor and hilum (OR=0.843, P=0.040), differentiation (moderate vs. high, OR=15.547, P=0.008; poor vs. high, OR=70.749, P=0.000), and cancer embolus (OR=24.769, P=0.004) were independent risk variables associated with lymph node metastasis.

  Conclusion  Distance between tumor and hilum was identified as an independent risk factor associated with lymph node metastasis in cT₁ NSCLC.