Lung cancer (LC) is a major public health issue because of its frequency, but especially because of the severity of this disease. The epidemiology has changed with an increased incidence in non-smokers and women. The ATS/ERS/IASLC classification of adenocarcinomas was modified in 2011, and they are now the most frequent histological subtype. More than half the cases of LC are diagnosed at the metastatic stage. Biopsies must provide tissue samples that are quantitatively large enough and of a good enough quality for diagnosis and to search for biomarkers. When the cancer seems to be localized, precise staging must be obtained. Treatment is based on the TNM classification. In localized stages, lobectomy associated with lymph node dissection is the standard therapy. Intraoperative chemotherapy improves survival in case of lymph node infiltration. Stereotactic radiation therapy and radiofrequency can be considered as specific cases. In cases with local progression, treatment is more controversial. In the presence of metastases, the goal is not a cure, but improving survival and quality of life. Numerous advances have been made with personalized treatment, (in particular in relation to the histological type and oncogenic addiction in tumors, access to new drugs, and improved management). Clinical research in thoracic cancer is very active. The fight against tobacco should remain a priority.