Accuracy of EUS in staging of T4 lung cancer

Background: Increasingly, EUS is being used to stage lung cancer. Direct mediastinal invasion (T4) by lung cancer is stage IIIb disease. Patients in this stage have a 5-year survival of less than 5% and generally are offered chemotherapy without surgery. This study evaluated the accuracy of EUS in detecting T4 lung cancer. Methods: The study included all patients with lung cancer who had EUS staging and subsequent staging at surgery, or for whom there was unequivocal confirmation of unresectability (T4) by thoracoscopy, thoracotomy or presence of malignant pleural effusion, or definite invasion of great vessels/adjacent organs on CT. Results: A total of 175 of 308 patients with lung cancer who underwent EUS over a 5-year period (1997-2002) had subsequent confirmatory tumor staging. Ten patients were found by EUS to have stage T4 tumors; 7 were confirmed to be T4 by either surgical exploration (2), CT demonstration of aortic invasion (3), or documentation of malignant pleural effusion (2). Three of the 10 (30%) patients found to have stage T4 tumors by EUS had T2 disease at surgery and underwent curative resection. Of the remaining 165 patients without evidence of T4 disease at EUS, only one was found to have aortic invasion (T4) at surgery. EUS had a sensitivity of 87.5%, specificity of 98%, positive predictive value of 70%, and a negative predictive value of 99% for detecting T4 disease. Conclusions: Caution is warranted when unresectability of lung cancer is based solely on tumor invasion into mediastinal soft tissue at EUS. Overstaging occurs when a tumor appears to invade the pleural layer without mediastinal organ invasion. Confirmation of unresectability by other diagnostic modalities is warranted in such instances.