Study objective: To identify factors associated with a misclassification of the true disease stage by comparing the differences between the clinical and pathologic stage of patients with early-stage non-small cell lung cancer (NSCLC).
Design: A prospective cohort study.
Setting: A multidisciplinary thoracic oncology clinic at a university-affiliated Veterans Affairs medical center.
Patient population: One hundred nine male veterans with clinical stage I/II NSCLC who had undergone thoracotomy with systematic lymph node dissection.
Methods: Prospective data were collected on all patients between September 1997 and April 2002. Logistic regression analysis was used to establish the odds ratio (OR) for predictors of changes in stage.
Results: A stage misclassification was found in 35.8% of patients (39 of 109 patients) after thoracotomy with lymph node dissection, and all but one patient were upstaged. Unsuspected nodal involvement (N stage) resulted in the upstaging of 16.5% of the patients, a change in tumor stage (T stage) resulted in the upstaging of 13.8% of the patients, a change in both stages resulted in the upstaging of 2.7% of patients, and the designation of metastatic disease resulted in the upstaging of 1.9% of the patients. The rate of unsuspected mediastinal lymph node involvement (pathologic stage N2) was 8.3% (9 of 109 patients), despite negative mediastinoscopy findings. Complete anatomic resection was performed in all patients. Advanced disease was found in 8.3% of the patients (9 of 109 patients) [stage IIIB or IV]. Having the primary tumor in a lower lobe location was the only statistically significant factor associated with upstaging (OR, 3.56; 95% confidence interval, 1.4 to 9.1). The effect of location was robust after controlling for tumor size and the prior performance of mediastinoscopy. Patient age, smoking history, weight loss, tumor size, and tumor histology were all found not to be associated with upstaging.
Conclusion: A lower lobe tumor location in patients with early-stage NSCLC appears to be associated with upstaging after surgery. We conclude that a tumor location in a lower lobe deserves special attention.