Pie chart showing incidences of<unk><unk> -cell lung cancers as compared to<unk> -cell carcinoma shown at right, with fractions of smokers versus<unk> smokers shown for each type The most common types of<unk>  are squamous-cell carcinoma, large-cell carcinoma, and adenocarcinoma, but several other types occur less frequently. A few of the less common types are pleomorphic, carcinoid tumor, salivary gland carcinoma, and unclassified carcinoma. All types can occur in unusual histologic variants and as mixed cell-type combinations.<unk> squamous-cell carcinoma almost occupies the half of<unk> . In the tissue classification, the central type contains about one-ninth. Sometimes, the phrase "not otherwise specified" (NOS) is used generically, usually when a more specific diagnosis cannot be made. This is most often the case when a pathologist examines a<unk>  number of malignant cells or tissue in a cytology or biopsy specimen. Lung cancer in people who have never smoked is almost universally<unk> , with a sizeable majority being adenocarcinoma. On relatively rare occasions, malignant lung tumors are found to contain components of both<unk>  and<unk> . In these cases, the tumors are classified as combined<unk> -cell lung carcinoma (c-SCLC), and are (usually) treated as "pure"<unk> . Lung adenocarcinoma Adenocarcinoma of the lung is currently the most common type of lung cancer in "never smokers" (lifelong<unk> smokers). Adenocarcinomas account for about 40% of lung cancers. Historically, adenocarcinoma was more often seen peripherally in the lungs than<unk>  and squamous-cell lung cancer, both of which tended to be more often centrally located. Recent studies, though, suggest that the "ratio of centrally to peripherally occurring" lesions may be converging toward unity for both adenocarcinoma and squamous-cell carcinoma. Squamous-cell lung carcinoma Photograph of a squamous-cell carcinoma: The tumour is on the left, obstructing the bronchus (lung). Beyond the tumour, the bronchus is inflamed and contains mucus. Squamous-cell carcinoma (SCC) of the lung is more common in men than in women. It is closely correlated with a history of tobacco smoking, more so than most other types of lung cancer. According to the Nurses' Health Study, the relative risk of SCC is around 5.5, both among those with a previous duration of smoking of 1 to 20 years, and those with 20 to 30 years, compared to "never smokers" (lifelong<unk> smokers). The relative risk increases to about 16 with a previous smoking duration of 30 to 40 years, and roughly 22 with more than 40 years. Large-cell lung carcinoma Large-cell lung carcinoma (LCLC) is a heterogeneous group of undifferentiated malignant neoplasms originating from transformed epithelial cells in the lung. LCLCs have typically comprised around 10% of all<unk>  in the past, although newer diagnostic techniques seem to be reducing the incidence of diagnosis of "classic" LCLC in favor of more poorly differentiated SCCs and adenocarcinomas. LCLC is, in effect, a "diagnosis of exclusion", in that the tumor cells lack light microscopic characteristics that would classify the neoplasm as a<unk> -cell carcinoma, squamous-cell carcinoma, adenocarcinoma, or other more specific histologic type of lung cancer. LCLC is differentiated from<unk>  primarily by the larger size of the anaplastic cells, a higher cytoplasmic-to-nuclear size ratio, and a lack of "salt-and-pepper" chromatin.
Non-small-cell lung carcinoma
Large-cell lung carcinoma
Adenocarcinoma of the lung
Giant-cell carcinoma of the lung
Sarcomatoid carcinoma of the lung
Squamous-cell carcinoma of the lung
Mesothelioma
Pulmonary sclerosing pneumocytoma