How should interlobar pleural invasion be classified? prognosis of resected T3 non-small cell lung cancer

Background. The results of surgical treatment for non-small cell lung cancer with interlobar pleural involvement and direct invasion of the other lobe have seldom been documented. Methods. Of 1,130 consecutive patients who were operated on for primary bronchogenic carcinoma between 1984 and 1997, we studied 132 patients who had complete resection of T3 non-small cell carcinoma. Results. The structures involved were as follows: parietal pleura, 49 patients; chest wall, 45; interlobar pleura, 19; main bronchus within 2 cm of the carina, 11; mediastinal pleura, 6; and diaphragm, 1. Patients with N2 disease had a significantly worse survival than those with N0 (p = 0.0054) and N1 disease (p = 0.0165). The survival of patients with involvement of the interlobar pleura was significantly worse than that of patients with T1 (p = 0.0001) or T2 disease (p = 0.0484), and was similar to that of patients with T3 disease (p = 0.9821). Conclusions. In patients with T3 disease, mediastinal lymph node involvement influenced survival significantly. Patients with involvement of the interlobar pleura should be regarded as having T3 lesions.