Lung cancer is the most common form of cancer in the United States, with more than 250,000 new cases each year. It is also the leading cause of death from cancer. Lung cancer is the second most common cancer (after skin cancer) affecting both sexes. It mostly affects those over 65 years of age, and is slightly more common in women.
Of the two categories of lung cancer, non-small cell lung cancer is the most common, accounting for nearly 90% of cases. It often grows and spreads less rapidly than small cell lung cancer. There are three types of non-small cell lung cancer — squamous cell carcinoma, adenocarcinoma and large cell carcinoma. Small cell lung cancer is less common than non-small cell lung cancer. It grows more rapidly and is more likely to spread to other organs in the body.
Smoking is the biggest single risk factor for lung cancer in general, although non-smokers may also develop small cell lung cancer. Exposure to substances such as asbestos, radon gas, uranium, arsenic, and diesel exhaust are also known to increase the risk of lung cancer. A family history of lung cancer also can be a risk factor.
Many lung cancers are identified when patients undergo a chest X-ray or CAT scan for an unrelated reason — a cold, cough, or other respiratory symptoms. Symptoms of lung cancer include: persistent cough, coughing of blood, shortness of breath, a hoarse voice, and recurring respiratory tract infections such as pneumonia, unusual fatigue, and weight loss.
Lung cancer usually begins in one lung. If left untreated, it can spread to lymph nodes or other parts of the chest, including the other lung. Lung cancer can also spread throughout the body to the bones, brain, liver or other organs.
Lung cancer survival is related to the cancer's stage — the size and location of the tumor, whether the cancer has spread to surrounding lymph nodes, and whether it has spread to distant sites.