Prevalence Of Mediastinal Metastases And Sensitivity Of Mediastinoscopy In Potentially Operable Non-Small Cell Lung Cancer Screened By Computerized Tomography And Positron Emission Tomography.
Back to 86th Annual Meeting
Back to Program Outline
OBJECTIVE: To estimate prevalence of N2 and N3 metastases in non-small cell lung cancer (NSCLC) patients deemed clinical stage I after both computerized tomography (CT) and positron emission tomography (PET) scans. To identify the role of mediastinoscopy in this carefully defined subset of patients.
METHODS: Secondary analysis of ACOSOG Z0050, a study in which utility of PET to preclude surgical resectability was ascertained in patients with suspected or histologically-confirmed clinical stage I, II, or IIIA (N2) NSCLC, provided subsets of patients deemed to be clinical T1N0 or T2N0 by CT alone, PET alone, or combined CT and PET. These three subsets were analyzed for prevalence of N2 and N3 disease missed by CT and/or PET, for rates and results of mediastinoscopy, and for final pathologic (pTxNx) staging.
RESULTS: Of 303 eligible Z0050 patients, 229 (76%), 145 (48%), and 156 (51%) were deemed clinical stage I by CT alone, PET alone, and combined CT and PET, respectively. Of the 156 patients defined by combined CT and PET, mediastinoscopy was performed on 14 (9%) patients and identified 3 patients with N2 or N3 disease (21% of mediastinoscopy patients, and 21% of all pN2 or pN3 patients). Lobar distribution of primary tumors for patients with mediastinoscopy was not significantly different (p=0.47) from the distribution for patients without mediastinoscopy. Of this subset of 156 patients, 17 patients did not have pulmonary resection, including 1 patient with N3 disease at mediastinoscopy, 10 patients with T4 or M1 disease on further workup, 2 patients with T4 disease on exploration, and 4 patients who refused surgery. The overall prevalence of histologically-confirmed N2 or N3 was 9% (14/156) in these patients deemed clinical stage I by combined CT and PET, including 3 patients who were pT1N2, 9 patients who were pT2N2, 1 patient who was pT2N3, and 1 patient who was pT4N2. Rates of mediastinal metastases were 5% (3/59) in pathologic T1 patients and 14% (10/70) in pathologic T2 patients. Of the 8 patients who recurred by 6 months, only 2 patients recurred in the mediastinum, one of whom had the mediastinum as the only site of recurrence.
CONCLUSIONS: Prevalence of missed N2 or N3 metastasis was 5% of pT1 patients and 14% of pT2 patients initially deemed clinical stage I by combined CT and PET. Histologically-confirmed N2 or N3 disease was identified in 21% of these patients by mediastinoscopy. More than 70% of patients with pN2 or pN3 disease were identified only after resection. Additional evaluation of the utility of mediastinoscopy in CT- and PET-negative clinical stage I NSCLC patients is needed.
Back to 86th Annual Meeting
Back to Program Outline
