Carcinoma of the lung is one of the most common malignancies in both men and women. It accounts for about 16% of all cancers diagnosed (20% of male and 12% of female cancers) making it the commonest malignancy and third most common cause of death in the UK. Its incidence has increased over the past decades in Europe and in the United States; in most developing countries, the incidence is lower. The incidence is now falling in men but continues to rise in women with lung cancer exceeding breast cancer as a cause of death in women in many parts of the UK.
At least 90% of cases of lung cancer are associated with exposure to tobacco smoke, which makes it the most clearly identified causation of a major cancer and in the long term the most obviously preventable. Genetic factors also play a role: 3p deletion, p53, k-ras and p16 mutations are common in lung carcinoma. Exposure to asbestos has a synergistic effect with smoking, as well as exposure to other substances, including minerals (such as nickel) and organic compounds (such as benzene). Although the median survival remains very poor at around 4 months a significant minority can be cured and many have their lives prolonged by appropriate management.
The consensus is that universal screening for early lung cancer by chest radiography and sputum cytology would be costly and impractical; however, high risk groups could benefit from periodic screening, such as workers exposed to inhalation of carcinogens or elderly people with a long history of smoking.
Classification of malignant tumors:
- Squamous cell carcinoma
- Adenocarcinoma (including bronchioloalveolar carcinoma)
- Large cell carcinoma
- Small cell carcinoma
- Neuroendocrine tumors (carcinoid tumor)
- Carcinomas of salivary gland-type
- Sarcoma and mixed epithelial-mesenchimal tumors
- Metastatic tumors