Since Mountain proposed the new staging system of non-small cell lung cancer in 1986, the indications for operation of NSCLC have been extended. However, operative mortality is from 3 to 6%. Therefore it is important to reduce unnecessary operation and to evaluate unresectability of tumor correctly, preoperatively The purpose of this study is to find out the causes of unresectability in patients who were initially thought to be resectable preoperatively.

By retrospective analysis, 64 patients out of 291 NSCLC patients who were undergone operation for curative resection in Seoul National University Hospital from Jan. of 1987 to Dec. of 1991, ware found to be unresectable at operating roost were selected for this study. Out of 64 patients,42 were evaluable. The analysis was focused on the change of pre- & post-operative staging and the causes of unresectability of tumors.

Among B2 patients with unresectable tumor who could be evaluated, preoperative CT finding showed resectable tumors in 55% (23 patients) and suspicious for unresectable tumors in 45% (19 patients). The causes of unresectability were technically unresectable T3 lesions in 7% (3 patients), T4 lesions in 62% (26 patients), N2 lesions in 17% (7 patients) and N3 lesions in 14% (6 patients).

The major causes of unresectability of NSCLC were pulmonary artery invasions. It is suggested that careful evaluation of mediastinal structure, especially great vessels by additional imaging technique other than CT (like MRI) is indicated in selected NSCLC cases.