Evaluation of TMN classification for lung carcinoma with ipsilateral intrapulmonary metastasis

Abstract

Background. Staging for lung cancer based on the TNM classification is an important predictive factor for prognosis. Recently, lung cancer with ipsilateral intrapulmonary metastasis (PM) was reclassified according to the revision of the TNM classification. To evaluate the prognostic importance of the new staging system for PM, we analyzed the postoperative survival of patients with non–small cell lung carcinoma. Methods. Of 1,002 consecutive patients who underwent operation for primary lung cancer between June 1984 and December 1996, we reviewed the medical record of 889 patients who underwent complete resection for non–small cell lung cancer. Results. We considered 89 patients (10.0%) to have synchronous ipsilateral PM. After reclassification to the former staging system revised in 1992, 5 patients were classified as stage I, 29 as stage IIIA, 48 as stage IIIB, and 7 as stage IV. In the new staging system revised in 1997, 48 patients were recategorized as stage IIIB, and 41 as stage IV. The 5-year survival of patients without PM (49.5%) was significantly better than that of patients with PM in primary-tumor lobe (29.6%, p = 0.002) or in nonprimary-tumor ipsilateral lobe (23.4%, p = 0.0002). Although the survival of patients with stage IV cancer without PM was significantly worse than that of patients with the new (1997) stage IV cancer with PM ( p = 0.02), it was similar to that of patients with the former (1992) stage IV cancer with PM. The survival of PM patients with N0 or N1 disease was significantly better than that of PM patients with N2 or N3 disease ( p = 0.001). Furthermore, in patients with the new (1997) stage IIIB cancer, the survival of N0 disease was better than that of N2 disease ( p = 0.007). Conclusions. Inasmuch as the prognosis of non–small cell carcinoma in patients with PM strongly correlated with N factor rather than PM factor, N factor should be reflected in a staging designation. We therefore consider the new TNM classification for PM reclassified in 1997 to be less acceptable for surgical-pathologic staging than the revision in 1992.