Objective: We studied clinical and pathological features of small peripheral adenocarcinoma of the lung, focusing on tumor typing based on Noguchi's classification of small adenocarcinoma and determining whether these tumors grew by replacing alveolar lining cells.
Methods: Subjects were 51 patients with small peripheral adenocarcinoma 2 cm or less in diameter resected between 1994 and 2001. Mediastinal and hilar lymph node dissection was done in 37 (72.5%). Patients were divided into 2 groups by replacement or nonreplacement tumors. We compared patient profiles, lymph node involvement, and recurrence and survival patterns.
Results: No significant difference was seen between groups in mean age, surgical procedure, or primary tumor location. Women predominated in replacement tumors at 71% vs 41%, p = 0.04. The incidence of lymph node metastasis at 40% vs 4.5%, p = 0.007 and distant metastasis at 47% vs 2.9%, p < 0.001 was significantly higher in nonreplacement than replacement tumors. Replacements tumor thus showed significantly better disease-free survival at 95% vs 53%, p < 0.001, and overall 3-year survival at 95.4% vs 62.7% than did nonreplacement tumors.
Conclusion: We found distant metastasis and lymph node involvement to be more frequent in nonreplacement than replacement small peripheral adenocarcinoma, on suggesting that pretreatment tumor typing and accurate nodal status determination are essential to improve disease staging.