Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.
Lung cancer is the most common cause of death due to cancer in both men and women throughout the world. The American Cancer Society estimated that 222,520 new cases of lung cancer in the U.S. will be diagnosed and 157,300 deaths due to lung cancer would occur in 2010. According to the U.S. National Cancer Institute, approximately one out of every 14 men and women in the U.S. will be diagnosed with cancer of the lung at some point in their lifetime.
Lung cancer is predominantly a disease of the elderly; almost 70% of people diagnosed with lung cancer are over 65 years of age, while less than 3% of lung cancers occur in people under 45
years of age.
Lung cancer was not common prior to the 1930s but increased dramatically over the following decades as tobacco smoking increased. In many developing countries, the incidence of lung cancer is beginning to fall following public education about the dangers of cigarette smoking and the introduction of effective smoking-cessation programs. Nevertheless, lung cancer remains among the most common types of cancers in both men and women worldwide. In the U.S., lung cancer has surpassed breast cancer as the most common cause of cancer-related deaths in women.
What causes lung cancer?
Smoking
The incidence of lung cancer is strongly correlated with cigarette smoking, with about 90% of lung cancers arising as a result of tobacco use. The risk of lung cancer increases with the number of cigarettes smoked and the time over which smoking has occurred; doctors refer to this risk in terms of pack-years of smoking history (the number of packs of cigarettes smoked per day multiplied by the number of years smoked). For example, a person who has smoked two packs of cigarettes per day for 10 years has a 20 pack-year smoking history. While the risk of lung cancer is increased with even a 10-pack-year smoking history, those with 30-pack-year histories or more are considered to have the greatest risk for the development of lung cancer. Among those who smoke two or more packs of cigarettes per day, one in seven will die of lung cancer.
Pipe and cigar smoking also can cause lung cancer, although the risk is not as high as with cigarette smoking. Thus, while someone who smokes one pack of cigarettes per day has a risk for the development of lung cancer that is 25 times higher than a nonsmoker, pipe and cigar smokers have a risk of lung cancer that is about five times that of a nonsmoker.
Tobacco smoke contains over 4,000 chemical compounds, many of which have been shown to be cancer-causing or carcinogenic. The two primary carcinogens in tobacco smoke are chemicals known as nitrosamines and polycyclic aromatic hydrocarbons. The risk of developing lung cancer decreases each year following smoking cessation as normal cells grow and replace damaged cells in the lung. In former smokers, the risk of developing lung cancer begins to approach that of a nonsmoker about 15 years after cessation of smoking.
Passive smoking
Passive smoking or the inhalation of tobacco smoke by nonsmokers who share living or working quarters with smokers, also is an established risk factor for the development of lung cancer. Research has shown that nonsmokers who reside with a smoker have a 24% increase in risk for developing lung cancer when compared with nonsmokers who do not reside with a smoker. An estimated 3,000 lung cancer deaths that occur each year in the U.S. are attributable to passive smoking.
Asbestos fibers
Asbestos fibers are silicate fibers that can persist for a lifetime in lung tissue following exposure to asbestos. The workplace is a common source of exposure to asbestos fibers, as asbestos was widely used in the past as both thermal and acoustic insulation. Today, asbestos use is limited or banned in many countries, including the U.S. Both lung cancer and mesothelioma (cancer of the pleura of the lung as well as of the lining of the abdominal cavity called the peritoneum) are associated with exposure to asbestos. Cigarette smoking drastically increases the chance of developing an asbestos-related lung cancer in workers exposed to asbestos. Asbestos workers who do not smoke have a fivefold greater risk of developing lung cancer than nonsmokers, but asbestos workers who smoke have a risk that is
fifty- to ninetyfold greater than nonsmokers.
Radon gas
Radon gas is a natural, chemically inert gas that is a natural decay product of
uranium. Uranium decays to form products, including radon, that emit a type of ionizing radiation. Radon gas is a known cause of lung cancer, with an estimated 12% of lung-cancer deaths attributable to radon gas, or
about 20,000 lung-cancer-related deaths annually in the U.S., making radon the second leading cause of lung cancer in the U.S. As with asbestos exposure, concomitant smoking greatly increases the risk of lung cancer with radon exposure. Radon gas can travel up through soil and enter homes through gaps in the foundation, pipes, drains, or other openings. The U.S. Environmental Protection Agency estimates that one out of every 15 homes in the U.S. contains dangerous levels of radon gas. Radon gas is invisible and odorless, but it can be detected with simple test kits.
Familial predisposition
While the majority of lung cancers are associated with tobacco smoking, the fact
that not all smokers eventually develop lung cancer suggests that other factors,
such as individual genetic susceptibility, may play a role in the causation of
lung cancer. Numerous studies have shown that lung cancer is more likely to
occur in both smoking and nonsmoking relatives of those who have had lung
cancer than in the general population. Recently, the largest genetic study of lung cancer ever conducted, involving over 10,000 people from 18 countries and led by the International Agency for Research on Cancer (IARC), identified a small region in the genome (DNA) that contains genes that appear to confer an increased susceptibility to lung cancer in smokers. The specific genes, located the q arm of chromosome 15, code for proteins that interact with nicotine and other tobacco toxins (nicotinic acetylcholine receptor genes).
Lung diseases
The presence of certain diseases of the lung, notably chronic obstructive
pulmonary disease (COPD), is associated with an increased risk (four- to sixfold the risk of a nonsmoker) for the development of lung cancer even after
the effects of concomitant cigarette smoking are excluded.
Prior history of lung cancer
Survivors of lung cancer have a greater risk of developing a second lung cancer than the general population has of developing a first lung cancer. Survivors of non-small cell lung cancers (NSCLCs, see below) have an additive risk of 1%-2% per year for developing a second lung cancer. In survivors of small cell lung cancers (SCLCs, see below), the risk for development of second lung cancers approaches 6% per year.
Air pollution
Air pollution from vehicles, industry, and power plants can raise the likelihood of developing lung cancer in exposed individuals. Up to 1% of lung cancer deaths are attributable to breathing polluted air, and experts believe that prolonged exposure to highly polluted air can carry a risk for the development of lung cancer similar to that of passive smoking.
Bronchitis is a disease of the respiratory system in which the bronchial passages become inflamed. There are two types of bronchitis, acute and chronic. Symptoms of acute bronchitis include frequent cough with mucus, lack of energy, wheezing, and possible fever. Treatment may require medication such as bronchial inhalers and predinsone. Supportive treatment is focused on relieving the symptoms with fever reducers, cough suppressants, and rest. Treatment may be more aggressive in patients with pre-existing conditions such as empyema, COPD, or cigarette smoking.
Lymph nodes help the body's immune system fight infections. Causes of swollen lymph nodes (glands) may include infection (viral, bacterial, fungal, parasites). Symptoms of swollen lymph nodes vary greatly. They can sometimes be tender, painful or disfiguring. The treatment of swollen lymph nodes depends upon the cause.
Chronic cough is a cough that does not go away and is generally a symptom of another disorder such as asthma, allergic rhinitis, sinus infection, cigarette smoking, GERD, postnasal drip, bronchitis, pneumonia, medications, and less frequently tumors or other lung disease. Treatment of chronic cough is dependant upon the cause.
COPD (chronic obstructive pulmonary disease) is a disorder that persistently obstructs bronchial airflow. COPD mainly involves three related conditions, chronic bronchitis, chronic asthma, and emphysema. Symptoms of COPD include chronic cough, shortness of breath, frequent respiratory infections, wheezing, morning headaches, and pulmonary hypertension. Treatment of COPD is focused on the related condition(s).
Ascites, the accumulation of fluid in the abdominal cavity is most commonly caused by cirrhosis of the liver. Some of the other causes of ascites include portal hypertension, congestive heart failure, blood clots, and pancreatitis. The most common symptoms include increased abdominal girth and size, abdominal bloating, and abdominal pain. Treatment depends on the cause of ascites.
Pleurisy, an inflammation of the lining around the lungs, is associated with sharp chest pain upon breathing in. Cough, chest tenderness, and shortness of breath are other symptoms associated with pleurisy. Pleurisy pain can be managed with pain medication and by external splinting of the chest wall.
Cancer is a disease caused by an abnormal growth of cells, also called malignancy. It is a group of 100 different diseases, and is not contagious. Cancer can be treated through chemotherapy, a treatment of drugs that destroy cancer cells.
Smoking is an addiction. More than 430,000 deaths occur each year in the U.S. from smoking related illnesses. Secondhand smoke or "passive smoke" also harm family members, coworkers, and others around smokers. There are a number of techniques available to assist people who want to quit smoking.
Hypercalcemia is a condition in which calcium levels in the blood are elevated. Hypercalcemia is associated with other conditions such as hyperparathyroidism, lung cancer, breast cancer, kidney failure, and elevated levels of vitamin D. Symptoms of hypercalcemia include constipation, nausea, abdominal pain, kidney stones, to name a few. Treatment depends on the cause of hypercalcemia.
Smoker's lung photo essay is a collection of pictures and microscopic slides of lung disease caused by cigarette smoking. Smoker's lung refers to the diseases and structural abnormalities in the lung caused by cigarette smoking.
Though it's difficult to say why some people develop cancer while others don't, research shows that certain risk factors increase a person's odds of developing cancer. These risk factors include growing older, family history of cancer, diet, alcohol and tobacco use, and exposure to sunlight, ionizing radiation, certain chemicals, and some viruses and bacteria.
Arsenic comes in two forms, inorganic and organic. Organic arsenic poisoning is usually not poisonous to humans; however, inorganic arsenic in large enough amounts can lead to shock and death. Symptoms of arsenic poisoning include nausea, abdominal pain, diarrhea, dehydration, dark urine, vertigo, delirium, shock, and death. Treatment for arsenic poisoning includes Hemodialysis and a variety of drugs.
Asbestos exposure lung disease is divided into three main types, asbestosis (lung scarring caused by asbestos fibers), disease of the lining of the lung (pleural plaques, scarring, or fluid accumulation), and lung cancer. Mesothelioma is cancer of the lining of the lung caused by asbestos exposure. Cancers of the larynx, throat, kidney, esophagus, and gallbladder have been linked to asbestos exposure. Treatment is dependant upon the type of condition related to asbestos exposure.
Nicotine is delivered to the brain through smoking, chewing, or sniffing tobacco. Nicotine is an addictive agent. Common names for nicotine products include smokes, cigs, butts, chew, dip, spit, or snuff. Habitual nicotine use leads to many debilitating medical conditions.
Mesothelioma is a form of cancer that forms in the chest lining (pleural mesothelioma), abdomen (peritoneal mesothelioma), and the heart sac (pericardial mesothelioma) in rare cases. Chest pain, shortness of breath, weight loss, and night sweats are symptoms and signs of mesothelioma. Treatment depends upon the stage and type of mesothelioma.
The lungs are primarily responsible for the exchange of oxygen and carbon dioxide between the air we breathe and the blood. Eliminating carbon dioxide from the blood is important, because as it builds up in the blood, headaches, drowsiness, coma, and eventually death may occur. The air we breathe in (inhalation) is warmed, humidified, and cleaned by the nose and the lungs.
Secondhand smoke can cause illness and disease in nonsmokers. Some of these conditions include lung cancer, heart disease, respiratory illnesses such as asthma, SIDS, bronchitis, and pneumonia. Learn how you can protect yourself and your family from secondhand smoke exposure in the home environment and workplace.
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