Effectiveness of thorax CT in detection of mediastinal lymph node metastasis at non-small cell lung carcinoma

Mediastinal lymph node metastasis is one of the most important risk factors which has an influence on stage, treatment and prognosis in patients with non-small cell lung cancer.In this study, effectivity of the computed tomography of the chest, a modality widely used for detection of mediastinal lymph node metastasis was evaluated.Ninetynine patients who have undergone mediastinoscopy and/or thoracotomy for non-small cell lung cancer in İnönü University School of Medicine Turgut Özal Medical Center between 02.06.1998 and 16.09.2008 were evaluated. Patients with large cell lung cancer were excluded. According to computed tomography findings, mediastinal lymph nodes equal or greater than 1 cm in short-axis diameter were considered to be pathologicaly enlarged. Cervical mediastinoscopy was performed in 24 of the 99 patients, resective surgery and mediastinal lymph node disection were performed in 75 patients. CT findings were compared with the results obtained histopathologically. Relationship between mediastinal lymph node invasion and cell type (squamous cell carcinoma or adenocarcinoma), location of the tumor (central/ peripheral, upper/lower lobes) and the effectivity of the CT for detection of mediastinal lymph node metastasis were investigated.In our study, overall rate of mediastinal lypmh node metastasis was 26.2% in all patients. Incidence rates of lymph node metastasis were not significantly different between the cell types. There was no significant difference in mediastinal lypmh node invasion rates between tumors located centrally and tumors located peripherally. Centrally located adenocarcinomas were determined to have higher lypmh node metastasis rates compared to centrally located squamous cell carcinomas. The rates of false positive results in patients with centrally located squamous cell carcioma and the rates of false negative results in patients with adenocarcinoma were higher when compared to other groups. Mediastinal lymph node invasion rate was significantly higher in lower lobe located tumors compared to upper lobe located tumors. Computed tomography was determined to have rates of 77% for sensitivity, 66% for specifity, 69% for accuracy, 25% for false positivity, 6% for false negativity, respectively.Invasive mediastinal staging such as mediastinoscopy or mediastinotomy is required to evaluate mediastinal lymph node metastasis accurately. Based on the findings of this study, we suggest that, CT scan of the chest can be helpful in directing the clinician to the most appropriate staging procedure and may reduce the number of the invasive procedures.