T1 lung cancer on CT: Frequency of extrathoracic metastases

Purpose: To determine the frequency of extrathoracic metastases in T1 non-small-cell lung cancer. Method: Ninety patients with T1 lung cancer identified on CT were included. Extrathoracic metastases were evaluated at the time of initial diagnosis and during a 1-year follow-up study. The frequency of metastases was compared in terms of cell type (squamous or nonsquamous), size (<2 cm or >2 cm), and the initial CT findings of the tumor. Results: Extrathoracic metastases were identified in 12 (13%) of 90 patients at the time of diagnosis and in 10 patients at the 1-year follow-up study (total, 22 of 90 [24%] patients). Tumors with ground-glass opacity on CT were associated with a significantly lower prevalence of metastases (p = 0.042). The area of ground-glass opacity was seen in 11 of 13 (85%) patients with bronchioloalveolar carcinoma and in 12 of 53 (23%) patients with adenocarcinoma other than bronchioloalveolar carcinoma (p < 0.001). There was no significant difference in the prevalence of metastases between squamous and nonsquamous cell carcinoma, between tumors smaller than 2 cm (n = 17) and larger than 2 cm in diameter(n = 73) and between tumors with or without mediastinal nodal metastases (p > 0.05). Conclusion: Extrathoracic metastases were apparent at the initial examination in 13% of patients and at the 1-year follow-up examination in 11% of patients. The prevalence is significantly lower in tumors with ground-glass opacity.