Intrapulmonary metastasis of non-small cell lung cancer: a prognostic assessment

According to the revised TNM classification in 1997, intrapulmonary metastasis within the same lobe of the primary tumor is designated as T4 and intrapulmonary metastasis in a different lobe is M1. However, their prognostic implications remain unclear. To assess their prognoses, we retrospectively analyzed the postoperative survival of patients with and without intrapulmonary metastasis.

From January 1982 to December 1996, 2340 patients with non-small cell lung cancer underwent surgical resection. The survival of patients having complete resection (n = 1534) was analyzed according to their intrapulmonary metastasis status: patients without intrapulmonary metastasis (n = 1393), those with metastasis in the same lobe (n = 105), and those with metastasis in a different lobe (n = 18). For comparison, patients with T4 disease without intrapulmonary metastasis in the same lobe (n = 54) and those with M1 disease without metastasis in a different lobe (distant M1, n = 18) were also analyzed.

The overall 5-year survivals were as follows: no intrapulmonary metastasis, 60%; stage T4 disease with no intrapulmonary metastasis, 34%; pulmonary metastasis in the same lobe, 34%; pulmonary metastasis in a different lobe, 11%; and distant M1, 6%. The differences in survival between patients with no pulmonary metastasis and those with metastasis in the same lobe (P <.001, log-rank test) and between patients with metastasis in the same lobe and those with distant M1 (P <.001) were significant. In contrast, there was no significant difference between patients with metastasis in the same lobe and those with T4 disease and no intrapulmonary metastasis or between patients with metastasis to a different lobe and those with distant M1.

Prognostically, intrapulmonary metastasis within the same lobe of the primary tumor was comparable with T4 and that in a different lobe was comparable with M1. In terms of postoperative prognosis, the revised TNM classification for intrapulmonary metastasis seems to be appropriate.