Background: The new classification of intrapulmonary metastases of lung cancer was proposed by the American Joint Committee on Cancer; however, the prognostic factors are heterogeneous and not yet fully clarified. In this study, the authors evaluated the prognostic factors for and the possible routes of intrapulmonary metastases.
Methods: The factors influencing the prognosis of primary resected nonsmall cell lung carcinomas with intrapulmonary metastasis in the resected specimens were evaluated according to the Cox proportional hazards model using a total of 66 nonsmall cell lung carcinomas. The possible routes of tumor spread via the blood or lymphatic vessels also were evaluated.
Results: The overall 5-year survival rate was 26.1%, and the statistical analysis of survival curves revealed a significant difference with regard to N classification (P = 0.042), site of intrapulmonary metastasis (P = 0.012), blood vessel invasion (P = 0.0046), and lymphatic vessel invasion (P = 0.0267); there were no significant differences in relation to age, sex, histology, differentiation, T classification, tumor size, stage, number of intrapulmonary metastases, or size of intrapulmonary metastasis. Multivariate analysis according to the Cox proportional hazards model identified a significant correlation between survival and blood vessel invasion (P = 0.044) and lymphatic vessel invasion (P = 0.042), suggesting independent prognostic significance. The correlation between site of intrapulmonary metastasis and the ratio of blood or lymphatic vessel invasion showed a significantly lower ratio of blood vessel invasion in cases with intrapulmonary metastases at sites central to the primary lesion or in different segment(s) compared with those in cases with intrapulmonary metastases at sites peripheral to the primary lesion or in ipsilateral different lobe(s), suggesting a possible lymphatic vessel route of tumor spread.
Conclusion: Blood vessel and lymphatic vessel invasion are important clinical factors in evaluating prognosis and the route of tumor spread in primary resected nonsmall cell carcinoma with intrapulmonary metastasis.