Abstract:

This study compares the two most frequently used methods, combined positron emission tomography-computed tomography (PET/CT) and mediastinoscopy, in detecting mediastinal lymph node metastases. It has been investigated whether PET/CT can be used as an alternative method to mediastinoscopy which is considered the gold standard in detecting mediastinal lymph node metastasis. Mediastinal lymph node metastasis is an important factor in treatment and prognosis of non-small cell lung cancer. A total of 102 patients diagnosed with non-small cell lung cancer by our clinic between 2012 and 2017, were enrolled in the study. In total 277 lymph nodes were compared with respect to their histopathologic results and their involvement in positron emission tomography. Specificity value of PET/CT was detected as 84.5% while its negative predictive value, positive predictive value and sensitivity were 82.7%, 69.5% and 66.6%, respectively. In patients who underwent only mediastinoscopy and whose frozen section samples did not demonstrate any metastatic involvement, when histopathological results of lymph node dissection performed by thoracotomy were analyzed, the negative predictive value of mediastinoscopy was calculated as 97%. In total 65 stations including 46 stations smaller than 1 centimeter and 19 stations larger than 1 centimeter, which did not demonstrate any uptake in PET/CT, were sampled. No metastasis was detected in histopathologic staging of these lymph nodes. For patients who do not demonstrate any uptake in mediastinal lymph nodes on PET/CT, invasive lymph node sampling is redundant. However, with the aim of avoiding unnecessary thoracotomies, invasive lymph node sampling is required, even though mediastinal lymph node uptake detected with PET/CT is below the threshold of malignancy.

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