The anatomic extent of disease, that is described by the TNM-classification remains the most important prognostic factor for lung cancer. Based on the changes in tumor characteristics, advances in diagnostic methods and treatment strategies, TNM-classifications are updated from time to time. The 7th TNM-classification was created on the basis of an international, large, and retrospective database. However due to retrospective data, there are still unanswered questions. Therefore "Prospective Lung Cancer Staging Project" is designed. In this project, in addition to the detailed evaluation of T, N, M descriptors; other factors, which were not considered to be relevant to lung cancer staging before, were also analyzed such as demographic data, histologic characteristics, certain biochemical and molecular prognostic and predictive factors. This project will be the basis of 8th TNM-classification for lung cancer. In this manuscript, we discuss the probable changes from the 7th TNM classification to the 8th.