The cells divide uncontrollably and may grow into adjacent tissue or spread to distant parts of the body. The mass of cancer cells will eventually become large enough to produce lumps, masses, or tumors that can be detected. Adenocarcinomas are cancers that form on a glandular surface, such as the lung, breast, prostate, ovary, or kidney. Leukemias and lymphomas are the cancers that occur in blood cell elements. Brain cancers, nerve cancers, melanomas, and certain testicular and ovarian cancers do not fall into a general category.
Metastatic cancers can spread from their original location to other parts of the body.
Lung cancer is cancer that usually starts in the lining of the bronchi, but can also begin in other areas of the respiratory system, including the trachea, bronchioles, or alveoli. Lung cancers are believed to develop over a period of many years. Nearly all lung cancers are carcinomas, a cancer that begins in the lining or covering tissues of an organ. The tumor cells of each type of lung cancer grow and spread differently, and each type requires different treatment. More than 95 percent of lung cancers belong to the group called bronchogenic carcinoma .