VALUE OF COMPUTED-TOMOGRAPHY AND MEDIASTINOSCOPY IN PREOPERATIVE EVALUATION OF MEDIASTINAL NODES IN NONSMALL CELL LUNG-CANCER - A STUDY OF 569 PATIENTS

The efficacy of computed tomography (CT) and mediastinoscopy as stagin g modalities to assess mediastinal lymph node status was evaluated in 569 patients with a presumed resectable non-small cell lung cancer (NS CLC). Computed tomography scan was performed in every patient and foll owed by mediastinoscopy in 331 and by thoracotomy in 477 patients. Med iastinal lymph nodes on CT larger than 1.5 cm were considered patholog ical. Overall, CT had a sensitivity of 69 %, a specificity of 71% and an accuracy of 71% in identifying mediastinal lymph node metastases. F or mediastinoscopy these figures were 72%, 100% and 89%, respectively. Computed tomography accuracy was distinctly lower in squamous cell ca rcinomas and in central tumors, as CT sensitivity was significantly lo wer in left-sided tumors. The positive predictive value (PPV) of CT in Tl lesions (29%) and PPV and negative predictive value (NPV) of CT in T2 squamous cell carcinomas (30% and 83%, respectively) were low, so questioning its use in those instances. We perform a mediastinoscopy i n every situation except for squamous cell carcinomas or small (less t han 3 cm) peripheral tumors in the absence of enlarged mediastinal lym ph nodes. This selective attitude is rewarding since a) the number of pN2 in the straight thoracotomy group was only 16% versus 41% in the m ediastinoscopy group, b) the exploratory thoracotomy rate in the strai ght thoracotomy group was low (4.6%).