POINT: Clinical stage IA non-small cell lung cancer determined by computed tomography and positron emission tomography is frequently not pathologic IA non-small cell lung cancer: The problem of understaging

Objective: There is an increase in interest in limited resection for clinical stage IA non-small cell lung cancer. The purpose of this study was to evaluate the accuracy of the diagnosis of clinical stage IA non-small cell lung cancer when determined by both computed tomography and positron emission tomography scans and to determine factors associated with understaging. Methods: A retrospective review of a prospectively maintained database of patients with non-small cell lung cancer was performed. Patients with clinical stage IA cancer determined by preoperative computed tomography and positron emission tomography scan were reviewed. The influence of the following factors was analyzed with regard to accuracy of clinical staging: tumor size, location, histology, and positron emission tomography positivity. Results: Of the 266 patients identified, cancer was correctly staged in 65%. Final pathologic stages also included IB (15%), IIA (2.6%), IIB (4.1%), IIIA (4.9%), IIIB (7.5%), and IV (.08%). Positive lymph nodes were found in 11.7% of patients. Pathologic T classification changed in 28.2% of patients. Cancer in patients with clinical tumor size greater than 2 cm (n = 68) was significantly more likely to be understaged than in patients with tumors 2 cm or less (49% vs 29%, P = .003). Cancer in patients with a positron emission tomography-positive (positron emission tomography+VE) primary evaluation (n = 218) was also more likely to be understaged (39% vs 15%, P = .001). Of patients with positron emission tomography+VE tumors greater than 2 cm, cancer was clinically understaged in 55%, compared with 32% for positron emission tomography+VE tumors 2 cm or less, and only 17% for positron emission tomography negative (-VE) tumors less than 2 cm. Conclusion: Clinical stage IA lung cancer is frequently understaged in patients. Size greater than 2 cm and positron emission tomography positivity are risk factors for understaging. Limited resection should be undertaken with caution in such patients.