|Lung cancer is the leading cause of cancer death in both men and women. It is also called carcinoma of the lung and refers to an abnormal growth within the lung tissue and the airways of the lungs (trachea and bronchi or tracheobronchial tree). Most lung cancers arise from the bronchial tree and are referred to as bronchogenic carcinomas.|
Lung cancer is classified into two major types according to the type of cell present in the tumor. These are small cell lung carcinoma (SCLC) and non-small cell lung carcinoma (NSCLC). SCLC (oat cell carcinoma, small cell undifferentiated carcinoma) is almost always caused by smoking, and accounts for about 13% of all new lung cancer cases ("Detailed Guide"). Typically, SCLC metastasizes into the brain, bone, bone marrow, liver, and/or lymph nodes.
NSCLC accounts for the remaining 87% of lung cancers, and can be further divided into three subtypes of cancer: Squamous cell carcinoma, adenocarcinoma, and large-cell undifferentiated carcinoma ("Detailed Guide"). About 25% to 30% of NSCLC cases are associated with smoking. NSCLC generally has a better prognosis than SCLC.
Other tumors may occur in the lung in addition to the two main types of lung cancer. Carcinoid tumors of the lung are slow-growing tumors that can be cured surgically, and account for less than 5% of lung tumors ("Detailed Guide"). Rarely, noncancerous (benign) tumors may also occur.
It is important to note that these classifications and subtypes of lung cancer are different types of cancer and have key differences in incidence, potential to spread, treatment options, and outcome. Lung cancer is generally characterized by rapid growth, early spread into nearby tissues and organs (metastasis), and rapid recurrence.
Risk: The greatest risk factor for lung cancer is tobacco smoke; 87% of lung cancers are thought to be caused by smoking, or by secondhand smoke ("Detailed Guide"). A diet low in fruits and vegetables can also increase the risk for lung cancer when concurrent in individuals who smoke or who are exposed to smoking. Those that stop smoking cigarettes, pipes, cigars, or marijuana can reduce their risk of lung cancer by one-third. Individuals who are exposed to smoking in the workplace have an increased risk for developing lung cancer.
Other risk factors include exposure to certain industrial agents, such as asbestos, arsenic, gasoline, ionizing radiation, nickel, aromatic hydrocarbons, and indoor air pollutants such as radon gas. There may also be a genetic predisposition to lung cancer.
Men have a 1 in 13 chance of developing lung cancer, and women a 1 in 18 chance ("Detailed Guide"). Lung cancer is unusual in individuals under 45 years of age; the average age at diagnosis with lung cancer is 70 years ("Detailed Guide").
Incidence and Prevalence: Lung cancer is the leading cause of cancer mortality in both men and women in the US. It is estimated that in 2005 there will be more than 170,000 new cases diagnosed, accounting for about 13% of all cancers ("Detailed Guide"). More individuals die from lung cancer than from breast, prostate, and colon cancers combined. The predicted mortality in 2005 is greater than 160,000 deaths, accounting for about 28% of all cancer-related deaths ("Detailed Guide"). Lung cancer is increasing worldwide at a rate of 0.5% per year, possibly due in part to increase of smoking in developing countries and industrial exposure. In all countries, rates are higher in urban than rural areas, and 2 to 6 times higher in males than females. In European countries, it is the leading cause of cancer incidence and mortality and accounts for about 21% of all cancer cases in men.