Objective: The purpose of this article was to investigate the validity of T4 classification of primary non-small cell lung cancer.
Methods: We retrospectively reviewed the clinical outcome of cases with pm 1 (n = 65) and T4 tumors invading adjacent organs (n = 36).
Results: When the pm 1 tumors were excised completely (n = 57), the prognosis of these cases was affected by the pN factor (5-year survival rate: pN 0-1; 70.1%, pN 2-3; 7.7%, p = 0.0002) and comparable to that of T2 diseases (pN 0-1 cases: p = 0.7315). The patients who underwent complete resection for their pm 1 tumors had a significantly better prognosis than cases with disseminations or malignant pleural effusions which had the same T4 classification (p < 0.0001). The prognosis of the patients who underwent complete resection for the tumors invading adjacent organs (classified under T4) was similar to that of T3 diseases (pN 0-1 cases: p = 0.7116).
Conclusions: Patients whose lung cancer is classified as T4 comprise 2 subgroups; those whose tumors can be completely resected, and those in whom complete resection is impractical. There is a significant difference in the management and the prognosis between these 2 groups although they share the same T4 classification.