Pathologic findings of lung tumors diagnosed on baseline CT screening.

Sixty-five people had a resection of their baseline screen-diagnosed lung cancers in the Early Lung Cancer Action Program. Forty-nine of the carcinomas were solitary, and 42 of these were adenocarcinomas. More than 1 carcinoma was found in 16 patients after pathologic examination of the lobectomy specimen; 15 of the 16 second carcinomas were adenocarcinomas, mixed subtype. Eighteen cases were submitted by local pathologists as Bronchioloalveolar carcinomas but were found to be invasive adenocarcinomas according to the World Health Organization classification by the Pathology Review Panel. Of the 65 resected cases, 57 were N0, 7 were N1, and 1 was N2. Upon careful review of the lobectomy specimens, 49 cases had solitary malignancies, 30 were Stage IA, 13 Stage IB, 3 Stage IIA, 2 Stage IIB, and 1 Stage IIIA on the basis of the American Joint Committee on Cancer/International Union for Cancer Control criteria. In the 16 cases found to have multiple malignancies, 6 had histologically different carcinomas and the remaining 10 had histologically identical malignancies. Eighty-three percent (76/92) of the carcinomas invaded the stroma with destruction of normal lung, and 21% (19/92) also showed either pleural or angiolymphatic invasion, even though 88% (57/65) of the carcinomas were free of lymph node metastases. This report describes the pathologic findings of the resected cases. Histopathologic distinctions among atypical adenomatous hyperplasia, bronchioloalveolar carcinomas, and invasive adenocarcinoma are described in detail.