A b s t r a c tAdenocarcinoma of the lung constituted 9% of all lung carcinomas in men 30 years ago.1 During the last several decades, its incidence has been increasing. [2][3][4][5][6][7][8] It is the most common cell type in females and in nonsmoking patients, and it is the most common tumor subtype in some regions of the world. 9-14 The incidence of bronchioloalveolar carcinoma (BAC) is also increasing.
15-17Many studies have evaluated pathologic prognostic features of adenocarcinomas, including cell types, architectural patterns, and stage. The majority these studies have not specifically examined Tl NO MO adenocarcinomas. Some studies used the previous definition of a stage I carcinoma and included patients with Nl metastases, other studies grouped adenocarcinomas with non-small cell carcinomas, and many have grouped Tl with T2 carcinomas.18~38 This has left a dearth of attention directed toward identifying prognostic factors for patients with Tl NO MO adenocarcinomas and BACs that undergo curative surgical excision. Prognostic features for this group of patients are important because the 5-year disease-free survival of patients with Tl NO MO adenocarcinoma is 66% to 85%. 39^6 Separation of adenocarcinomas from other pulmonary carcinomas and examining the subset of patients with Tl disease is essential to understand the metastatic potential and prognostic strength of pathologic factors of the different tumors included under the rubric of stage I adenocarcinoma and BAC. 43 In addition, the prognostic significance of distinguishing between BAC and conventional adenocarcinoma and the threshold for amount of central fibrosis allowable within the BAC category for prognostication has not been defined fully. Finally, the identification of prognostic variables within this group of patients is important for future adjuvant therapy studies to identify the subset of patients that are at higher risk of having an adverse carcinoma-related outcome.We retrospectively studied 218 cases of completely resected, surgically staged, Tl NO adenocarcinomas and