Background: In the current TNM staging system revised in 1997 for lung cancer, intrapulmonary metastases (PM) are classified into two categories: PM1 (in the same lobe of the primary tumor), designated as T4; and PM2 (in a different lobe), as M1. There have been no large-scale analyses on PM in non-small cell lung cancer (NSCLC) patients. We collected data nationwide in Japan for 7408 lung cancer patients undergoing surgical resection during a single year, 1994. We analyzed the long-term survival of NSCLC patients to evaluate the prognostic impact of PM in relation to other prognostic factors.
Method: Medical records of 6525 NSCLC patients undergoing surgical resection during a single year, 1994, were analyzed as a subset work of the Japanese Joint Committee of Lung Cancer Registry. The committee sent a questionnaire on outcome and clinicopathological profiles to 303 institutions.
Results: There were 6080 PM0 (no PM), 317 PM1, and 128 PM2 patients. The 5-year survival rates were 55.1% for PM0 patients, 26.8% for PM1, and 22.5% for PM2 patients, respectively. The differences in survival between patients with PM0 and PM1 and between patients with PM0 and PM2 were significant (p < 0.001, respectively); the difference in survival was not significant between patients with PM1 and PM2 (p = 0.298). In R0 and N0 patients, survival differences were similar for PM0, PM1, and PM2 patients. Significant survival difference was detected between T3 and PM1 (p = 0.0317) and between PM1 patients and T4 patients excluding PM1 (p = 0.0083). The 5-year survival rates of PM2 patients and M1 patients excluding PM2 were 22.5% and 20.5%, respectively, and there was no significant difference between the groups (p = 0.434).
Conclusion: There was no significant survival difference between NSCLC patients with PM1 and PM2. The survival of patients with PM1 was between that of the T3 and T4 patients excluding PM1.