A clinical analysis of small-sized lung cancers with advanced disease was conducted on a total of 58 patients: 34 diagnosed as T1N2, 6 as T1N3, 9 as T1M1, and 9 as T4 due to pleural dissemination. The cumulative 5-year survival rate after surgery for the 34 patients with a T1N2 lesion was 17.4%. Of these 34 patients, 24 underwent a curative operation resulting in a 5-year survival rate of 23.7%, but the remaining 10 patients, who underwent a non-curative operation, had a 5-year survival rate of 0%. Extended lymph node dissection for N3 disease has only been performed in recent years, so it is not yet clear whether it will affect the survival rate or not. T4 disease due to pleural dissemination and T1M1 disease associated with intrapulmonary metastasis encountered at thoracotomy could be expected to have relatively long-term survival with the combined use of systemic immunochemotherapy after surgery. In cases diagnosed as T4 due to pleural dissemination, we have recently employed resection of the primary lesion with parietal pleurectomy as the standard operative procedure. For cases of T1M1 with intrapulmonary metastasis confined to the same lobe as the primary lesion, a lobectomy is usually performed, while for cases with intrapulmonary metastasis extending to another lobe, a lobectomy with enucleation of metastatic nodules or pneumonectomy is most often performed instead of an exploratory thoracotomy.