Doctor's Notes on Lung Cancer
Lung cancer is a group of diseases characterized by abnormal cell growth (cancers, tumors) in lung tissues. The primary signs and symptoms of lung cancer are as follows: shortness of breath, chest pain, persistent cough and/or coughing up blood, wheezing or hoarseness and respiratory infections. Indirect signs and symptoms due to chemicals released from the cancer cells may include finger clubbing, new bone formation, blood clots, or nervous system degeneration and electrolyte abnormalities. There are many different types of lung cancers but most share these signs and symptoms.
Lung cancer is caused by abnormal growth and multiplication of lung cells; this is considered primary lung cancer while many other cancers in the lungs are due to metastatic cancer cells that originated in organs other than the lung that traveled through the body to reach the lungs. About 90% of lung cancers are due to smoking; other potential causes are air pollution, asbestos exposure, radon exposure, and lung diseases such as tuberculosis. Exposure to arsenic, chromium, nickel, ethers and aromatic hydrocarbons increase the risk of developing lung cancer.
Lung Cancer Symptoms
Up to one-fourth of all people with lung cancer may have no symptoms when the cancer is diagnosed. These cancers usually are identified incidentally when a chest X-ray is performed for another reason. The majority of people, however, develop symptoms. The symptoms are due to direct effects of the primary tumor, to effects of metastatic tumors in other parts of the body, or to disturbances of hormones, blood, or other systems caused by the cancer.
- A new cough in a smoker or a former smoker should raise concern for lung cancer.
- A cough that does not go away or gets worse over time should be evaluated by a health care professional.
- Coughing up blood (hemoptysis) occurs in a significant number of people who have lung cancer. Any amount of coughed-up blood is cause for concern.
- Chest pain is a symptom in about one-fourth of people with lung cancer. The pain is dull, aching, and persistent.
- Shortness of breath usually results from a blockage to the flow of air in part of the lung, collection of fluid around the lung (pleural effusion), or the spread of tumor throughout the lungs.
- Wheezing or hoarseness may signal blockage or inflammation in the lungs that may go along with cancer.
- Repeated respiratory infections, such as bronchitis or pneumonia, can be a sign of lung cancer.
Symptoms of metastatic lung tumors depend on the location and size. About 30% to 40% of people with lung cancer have some symptoms or signs of metastatic disease.
- Lung cancer most often spreads to the liver, the adrenal glands, the bones, and the brain.
- Metastatic lung cancer in the liver may cause a loss of appetite, feeling full early on while eating, and otherwise unexplained weight loss.
- Metastatic lung cancer in the adrenal glands also typically causes no symptoms.
- Metastasis to the bones is most common with small cell cancers but also occurs with other lung cancer types. Lung cancer that has metastasized to the bone causes bone pain, usually in the backbone (vertebrae), the large bones of the thigh (the femurs), the pelvic bones, and the ribs.
- Lung cancer that spreads to the brain can cause difficulties with vision, weakness on one side of the body, and/or seizures.
Paraneoplastic syndromes are the remote, indirect effects of cancer not related to direct invasion of an organ by tumor cells. Often they are caused by chemicals released from the cancers. Symptoms include the following:
- Clubbing of fingers -- the depositing of extra tissue under the fingernails
- New bone formation -- along the lower legs or arms
- Increased risk of blood clots in the arms, legs, or lungs
- Low sodium levels
- High calcium levels
- Low potassium levels
- Degenerative conditions of the nervous system otherwise unexplained.
Lung Cancer Causes
- Cigarette smoke contains more than 4,000 chemicals, many of which have been identified as causing cancer.
- A person who smokes more than one pack of cigarettes per day has a 20-25 times greater risk of developing lung cancer than someone who has never smoked.
- Once a person quits smoking, his or her risk for lung cancer gradually decreases. About 15 years after quitting, the risk for lung cancer decreases to the level of someone who never smoked.
- Cigar and pipe smoking increases the risk of lung cancer but not as much as smoking cigarettes.
About 90% of lung cancers arise due to tobacco use. The risk of developing lung cancer is related to the following factors:
- The number of cigarettes smoked
- The age at which a person started smoking
- How long a person has smoked (or had smoked before quitting)
Other causes of lung cancer, including causes of lung cancer in nonsmokers, include the following:
- Passive smoking, or secondhand smoke, presents another risk for lung cancer. An estimated 3,000 lung cancer deaths occur each year in the U.S. that are attributable to passive smoking.
- Air pollution from motor vehicles, factories, and other sources probably increase the risk for lung cancer, and many experts believe that prolonged exposure to polluted air is similar to prolonged exposure to passive smoking in terms of risk for developing lung cancer.
- Asbestos exposure increases the risk of lung cancer nine times. A combination of asbestos exposure and cigarette smoking raises the risk to as much as 50 times. Another cancer known as mesothelioma (a type of cancer of the inner lining of the chest cavity and the outer lining of the lung called the pleura, or of the lining of the abdominal cavity called the peritoneum) is also strongly associated with exposure to asbestos.
- Lung diseases, such as tuberculosis (TB) and chronic obstructive pulmonary disease (COPD), also create a risk for lung cancer. A person with COPD has a four to six times greater risk of lung cancer even when the effect of cigarette smoking is excluded.
- Radon exposure poses another risk.
- Radon is a byproduct of naturally occurring radium, which is a product of uranium.
- Radon is present in indoor and outdoor air.
- The risk for lung cancer increases with significant long-term exposure to radon, although no one knows the exact risk. An estimated 12% of lung cancer deaths are attributable to radon gas, or about 21,000 lung cancer-related deaths annually in the U.S. Radon gas is the second leading cause of lung cancer in the United States after cigarette smoking. As with asbestos exposure, smoking greatly increases the risk of lung cancer with radon exposure.
- Certain occupations where exposure to arsenic, chromium, nickel, aromatic hydrocarbons, and ethers occurs may increase the risk of lung cancer.
- A person who has had lung cancer is more likely to develop a second lung cancer than the average person is to develop a first lung cancer.
Fact: Quitting has almost-immediate benefits. Your circulation will improve and your lungs will work better. Your lung cancer risk will start to drop over time. Ten years after you kick the habit, your odds of getting the disease will be half of what they are now.
Lung Cancer : Signs and Symptoms QuizQuestion
Lung cancer is a disease in which lung cells grow abnormally in an uncontrolled way.See Answer
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.