Lung cancer is a malignant growth that starts in the respiratory system, usually in the lining of the bronchi (the main airways of the lungs). Lung cancer is the leading cause of cancer death in both men and women. It is believed to develop slowly over a period of many years. Many patients are not diagnosed until their lung cancer reaches an advanced stage. Two Types of Lung Cancer Nearly all lung cancers are carcinomas, a cancer that begins in the lining or covering epithelium of an organ. The tumor cells of each type of lung cancer grow and spread differently. Lung cancers are generally divided into two types: Non-small cell lung cancer, the most common type, accounting for 85 to 90 percent of cases Small cell lung cancer, which grows rapidly and spreads quickly to other organs Lung cancer usually does not cause symptoms right away, but symptoms often appear after the tumor begins growing. A cough is the most common sign of lung cancer. Since most smokers cough, this symptom is often ignored. Other symptoms include constant chest pain, shortness of breath, wheezing, recurring lung infections (such as pneumonia), bloody or rust-colored sputum, hoarseness, and fever for unknown reason. Like all cancers, lung cancer can cause fatigue, loss of appetite, loss of weight, headache, pain in other parts of the body, and bone fractures. None of these symptoms is a sure sign of lung cancer. Only a doctor can tell whether cancer or another problem is causing the symptoms. Risk Factors Several risk factors make you more likely to develop lung cancer. Smoking is the leading cause of lung cancer. Nearly 90 percent of cases are thought to be a result of smoking. Additional risk factors include exposure to secondhand smoke, a personal or family history of lung cancer, asbestos exposure, talcum powder exposure, cancer-causing agents in the workplace (such as uranium, arsenic, and coal products), radon exposure, vitamin A deficiency, and air pollution. Diagnosis If you have lung cancer, it's important to find out what kind it is. Each type requires different treatment. To diagnose the disease, your doctor will perform a physical exam, as well as check for risk factors, signs of lung cancer, and other health problems. Other procedures used to diagnose lung cancer may include the following: Chest X-ray: a diagnostic test that looks for any mass or spot on the lungs. Other special X-rays: diagnostic tests that use invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film to provide more precise information about the size, shape, and position of a tumor. Computed tomography scan (also called a CT or CAT scan): a diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce cross-sectional images (often called slices) of the body. Sputum cytology: a study of phlegm (mucus) cells under a microscope. Needle biopsy: a test in which a sample of the mass is removed from the lungs and evaluated under a microscope. Bronchoscopy: the examination of the bronchi (the main airways of the lungs) using a flexible tube (bronchoscope) passed down the mouth or nose. Mediastinoscopy: a process in which a small cut is made in the neck so that a tissue sample can be taken from the lymph nodes along the windpipe and the major bronchial tube areas to evaluate under a microscope. X-rays and scans of the brain, liver, bone, and adrenal glands: tests to determine if the cancer has spread from where it started into other areas of the body. Treatment Clinical staging of lung cancer determines what treatment strategy offers the best potential outcome. Lung cancer may be treated with one or a combination of the following: surgery, conventional chemotherapy, targeted therapy or other medications, radiation therapy, and laser therapy. Your doctor will decide on the specific treatment after reviewing your medical history and other factors.