Relationship between the Size and Location of the Mass and Hilar and Mediastinal Lymph Node Metastasis in Early and Locally Advanced Non-small Cell Lung Cancer

Objective: To determine whether there is a relationship between the size and location of the mass and lymph node metastasis in non-small cell lung cancer. Study Design: Observational study. Place and Duration of Study: Department of Medical Oncology of Trakya University, from November 2013 to November 2018. Methodology: Records of 112 patients, who were followed up for non-small cell lung cancer, were retrospectively reviewed. Patients with distant organ metastasis (M1) and distant lymph node metastasis (N3), a previous history of malignancy, synchronous or metachronous tumors, and those for whom required data could not be obtained were excluded. Lymph nodes were evaluated according to pathology reports in patients undergoing invasive procedures. In patients without invasive procedures, lymph node larger than 1 cm in thorax CT, SUV above 2.5 in PET, and acceptance of metastasis at the Oncology Council was considered decisive. Diameter of the tumor, the shortest distance between the tumor and the mediastinum, the shortest distance between the tumor and the hilum, and the diameters of the largest mediastinal or hilar lymph nodes were measured from the thoracic computed tomography (CT) taken at the time of the diagnosis. The relationship between these values and lymph node metastasis was statistically evaluated. Results: Upon consideration of thoracic CT measurements, lymph node metastasis was found to have a statistically significant relationship with tumors with a large diameter (>55 mm) (p<0.001), tumors close to the mediastinum (<7 mm) (p=0.003), and tumors close to the hilum (<60 mm) (p=0.045). The evaluation of the distinctiveness of markers in diagnosis through ROC analysis showed AUC of 0.70 (p<0.001) for the largest tumor diameter, and the risk of lymph node metastasis was higher for lesions above 55 mm. Conclusion: In thorax CT, Large tumor size, tumor close to mediastinum, tumor close to hilum, large lymph node, and high SUV value of lymph node in PET-CT are associated with increased chances of metastasis.