Lung cancer

Lung cancer is the leading cause of cancer death. More than 20 types of malignant and benign tumors have been identified as originating in the lungs. A benign tumor is a mass of abnormal tissue that does not spread and can be completely removed surgically. It is not life-threatening and is not likely to recur. A malignant tumor, however, is an abnormal growth of cells that can invade and destroy nearby tissue or organs and can spread to other parts of the body.

Cigarette smoking accounts for 85 percent of all lung cancers. Other risk factors for lung cancer include exposure to asbestos and other industrial carcinogens, second-hand smoke, and high concentrations of radon. Primary lung cancer is uncommon in nonsmokers, but cancer of the breast, colon, prostate, kidney, thyroid, bone, or other organs may spread to the lungs. The symptoms of lung cancer are cough that produce sputum, containing pus and sometimes blood, shortness of breath, fever, chest pain, hoarness, loss of appetite and weight.

Lung cancer is a very serious disease and has a very poor outlook. However, the outcome depends on the extent of the disease when it is covered, the general health and age, the cell type of cancer, how rapidly it growths, and what type of therapy is given. Only 20 to 25 percent of all lung cancers can be removed surgically at the time of initial diagnosis. Once symptoms of lung cancer appear, the disease may be fairly well advanced and not treatable by operation.

Basically, there are three treatment options for lung cancer: surgery, chemotherapy, and radiation therapy. Laser surgery can be used to restore breathing when tumors obstruct central air passageways. Usually, this is done only when surgical removal of cancer is not possible.

Ex. 20. Read the text in paragraphs. Define the main subject of each paragraph: