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Objective: The purpose of this study was to identify risk factor for recurrence and poor prognosis after surgical resection of small adenocarcinoma of the lung.
 Materials and Methods: One hundred and twenty seven patients who had pathologic stage IA adenocarcinoma of the lung < 20mm in diameter and who had undergone a lobectomy with mediastinal lymph node dissection were retrospectively reviewed. The relationships between clinicopathologic variables, including area ratio of bronchioloalveolar carcinoma (BAC) and Epidermal Growth Factor Receptor (EGFR) gene mutation status, and clinical outcomes were examined.
 Results: Based on the percentage of BAC component, 127 patients were classified as follows, group I (BAC, 100%); 26, group II (BAC, more than 50% and less than 100%); 46, group III (BAC, more than 0% and less than 50%); 18, and group IV (BAC, 0%); 37. Female gender (p=0.01) and never smoking status (p=0.0003) were more frequent in group I and II. EGFR mutations in exon 19 and exon 21 were observed in 64 patients (50.4%). EGFR mutations were more frequently found in female gender (p=0.006) and never smoker (p=0.001).
 Among the clinicopathologic variables examined, serum CEA level (P=0.047) and area rate of BAC component (P=0.003) were significantly related to a high risk of recurrence according to univariate analysis. Multi-logistic regression model indicated that area ratio of BAC component was the only independent risk factor for recurrence (P=0.03). Regarding survival, ever smoking status, high CEA level (>5) and low ratio of BAC component (<50%) were significantly related to the poor overall survival (OS) (P=0.004, <0.0001, 0.008), disease-specific survival (P=0.04, 0.003, 0.0009), and disease-free survival (DFS) (P=0.04, 0.003, 0.0008). A Cox proportional hazards model indicated that high age (P=0.03) and low ratio of BAC component (P=0.046) was independent risk factor for a poor OS. Low ratio of BAC component was also the independent risk factor for poor disease-specific survival (P=0.03) and DFS (P=0.03).
 Conclusion: Low ratio of BAC component was independent risk factor for both recurrence and a poor prognosis for patients with stage IA adenocarcinoma of the lung < 20mm. On the other hand, EGFR was not risk factor for both recurrence and survival.

99th AACR Annual Meeting-- Apr 12-16, 2008; San Diego, CA