Lung carcinoma is a diagnostic category that includes all the malignant tumors that originate from the tissues that make up the bronchi and lung parenchyma. For this reason, sarcomas and lymphomas that arise in the context of lung structures must be distinguished from this category.
The majority of malignant lung tumors is represented by lung carcinoma, while sarcomas and lymphomas constitute less than 0.5% of this series. Less than 5% of lung cancers are benign or low-grade tumors.
A further distinction must be made between primary neoplasms and secondary neoplasms. In fact, while the former originate from the pulmonary structures, the latter are represented by metastases of neoplasms that originate in other organs such as, for example, the kidney, the liver, the breast and the prostate.
Lung cancer and cigarette smoking
Cigarette smoking is considered the main etiological agent for the development of lung cancer. According to a study using statistical projections, it is responsible for approximately 90% of fatal lung cancers in developed countries. In particular, again according to a study, in the USA cigarette smoking is responsible for the development of 87% of cases of lung cancer with an incidence that increases considerably if the first exposures occur within 25 years of age.
Cigarette smoke contains approximately 60 known carcinogens, including radioisotopes from radon decay, benzopyrene, and some nitrosamines. Furthermore, the nicotine present is able to depress the immune response, decreasing the surveillance and killing capacity of neoplastic cells by T lymphocytes and NK lymphocytes.
Asbestos, in addition to being implicated in the pathogenesis of asbestosis and pleural mesothelioma, shows a synergistic role with tobacco smoke in the development of lung carcinoma. In Great Britain it has been estimated that 2-3% of fatal cancers are caused by asbestos. Although there are no definitive data yet, exposure to smog and air pollution is implicated in the pathogenesis of fatal lung cancer.
The prognosis is based on the histological type and stage of the tumor. Small cell lung cancer has a poor prognosis, although radiotherapy and targeted chemotherapy interventions in the locally delimited form are able to increase 5-year survival by up to 5%. In forms of non-small cell lung cancer, survival depends above all on the classification, although the presence of concomitant pathologies and the Karnofsky index calculated for the patient under observation must always be considered.