Lung cancer takes many years to develop. However, changes in the lung can begin almost immediately upon exposure to carcinogens. Soon after exposure begins, microscopic examination of the tissue lining the bronchi will reveal a few unusual cells. With continued exposure, more abnormal cells appear. These cells may be on their way to becoming cancerous and forming a tumour.
The symptoms of the cancer vary depending on several factors, including where in the lung the tumour is found. If the cancer is located in one of the bronchi, it can irritate the lining of the bronchus and cause a chronic cough. The cancerous area may bleed when a person coughs.
If the tumour grows larger, it may gradually fill the bronchus so that air can't pass in or out. A blocked bronchus may also cause repeated lung infections or pneumonia.
The lungs have extensive networks of blood and lymph vessels. Cancer cells may grow into these vessels and be carried by the blood or lymph to circulate through the body. The cancer cells may then be deposited in other organs of the body. It is also possible for cancer cells that begin in other organs to spread to the lungs.
Smoking is the number one cause of lung cancer. Cigarette smoke contains more than 4,000 different chemicals, many of which are proven carcinogens, while hundreds of others increase the cancer-causing power of carcinogens. Many of these chemicals also affect the nonsmoker inhaling secondary smoke. Men who smoke are estimated to be 22 times more likely to develop lung cancer than those who do not, while women who smoke are estimated to be 12 times more likely, If you stop smoking, the risk of cancer decreases steadily each year as abnormal cells are replaced by normal cells.
Another leading cause of lung cancer is on-the-job exposure to carcinogens. Asbestos is perhaps the best known of the industrial substances associated with lung cancer, but there are many cancer-causing substances such as asbestos, uranium, arsenic, and certain petroleum products, that people may deal with at work. Lung cancer occurs most often in people over 50 who have long histories of cigarette smoking.
Symptoms of lung cancer include, chronic cough, coughing up blood, wheezing and chest pain.
Surgery may cure lung cancer. Radiation therapy in combination with chemotherapy is also used to treat lung cancer.