Excellent survival in a subgroup of patients with intrapulmonary metastasis of lung cancer

Background. Recently, intrapulmonary metastases in non-small cell lung cancer have been considered to have less influence on prognosis than extrapulmonary metastases. We report a subgroup found among patients with intrapulmonary metastases showing a good prognosis. Methods. A retrospective study was performed on 236 consecutive patients with non-small cell lung cancer who underwent surgical resection of their tumors. Intrapulmonary metastases were found histopathologically in 50 of them, and their clinicopathologic features were investigated. Results. Analysis of postsurgical results revealed a subgroup of patients showing excellent prognosis (n = 15). They had well-differentiated adenocarcinomas with bronchioloalveolar spread and pT1–2 N0, without vascular or lymphangitic invasion. Their actuarial 5-year survival rate was 100%, with a mean survival interval to date of 28 months. However, none of the other 35 patients survived for 5 years, with a mean survival interval to date of 11 months. Conclusions. We have clarified that patients with histopathologically diagnosed intrapulmonary metastases from non-small cell lung cancer do not constitute a homogeneous group. Pulmonary metastases with good prognosis, which are considered to be hematogenous metastases, may be benign lesions such as adenomatous or atypical adenomatous hyperplasias mimicking malignant tumors.