Lung Cancer

Lung cancer is uncontrolled growth of abnormal cells in lung tissue. Normally, the body maintains a system of checks and balances on cell growth so that cells divide to produce new cells only when needed. Disruption of this system of checks and balances on cell growth results in an uncontrolled division and production of cells that eventually forms a mass known as a tumor.

There are two major types of lung cancer: non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Non-small cell lung cancer is much more common. It usually spreads to different parts of the body more slowly than small cell lung cancer. Squamous cell carcinoma, adenocarcinoma, and large cell carcinoma are three types of non-small cell lung cancer. Small cell lung cancer also called oat cell cancer, accounts for about 20% of all lung cancer. Tumors can be benign or malignant; but mostly when we stalk about cancer we refer to tumors that are considered malignant. Benign tumors can usually be removed and do not spread to other parts of the body. Malignant tumors, on the other hand, grow aggressively and invade other tissues of the body, allowing entry of tumor cells into the bloodstream or lymphatic system which spread the tumor to other sites in the body. This process of spread is termed metastasis; the areas of tumor growth at these distant sites are called metastases. Since lung cancer tends to spread, or metastasize, very early in its course, it is a very life-threatening cancer and one of the most difficult cancers to treat. While lung cancer can spread to any organ in the body, certain organs - particularly the adrenal glands, liver, brain, and bone - are the most common sites for lung cancer metastasis. Tumor metastases are made up of the same type of cells as the original, or primary, tumor.

Lung cancer is responsible for the most cancer deaths in both men and women throughout the world. Lung cancer is the most common form of cancer in men worldwide and the fifth most common form of cancer in women. Lung cancer has surpassed breast cancer in causing the most cancer-related deaths in women in the US. Lung cancer wasn't common before the 1930s but increased as tobacco smoking increased. In many developing countries the frequency of lung cancer is beginning to fall following public education about the dangers of cigarette smoking and effective smoking cessation programs. The rate of lung cancer cases appears to be dropping among white and African-American men in the United States, while it continues to rise among both white and African-American women. The general prognosis of lung cancer is poor, with overall survival rates of about 15% at 5 years.

Smoking is the number one cause of lung cancer . A total of 90% of lung cancer cases are related to smoking. The risk of lung cancer is 30 times greater in smokers than in nonsmokers. One in seven people who smoke at least two packs per day will die of lung cancer. Cigar and pipe smoke doubles the risk of developing lung cancer. Cigarette smoke contains more than 4,000 different chemicals, many of which are proven cancer-causing substances, or carcinogens. Between 5,000 to 10,000 Americans develop lung cancer each year from secondhand smoke. Exposure to air pollution, radiation and industrial chemicals, arsenic, nickel, chromium and asbestos increase the risk of lung cancer. Asbestos alone increases the risk of getting lung cancer four times. The combination of asbestos and smoking increase the risk 90 times. Asbestos exposure is also associated with mesothelioma, a type of cancer that starts in the lining of the chest. There is some evidence that women who smoke have a greater risk than men who smoke of developing the disease. Many of the chemicals in tobacco smoke also affect the nonsmoker inhaling the smoke, making secondhand smoking another important cause of lung cancer. It is responsible for approximately 3,000 lung cancer deaths annually. Radon is considered to be the second leading cause of lung cancer in the U.S. today. Radon gas can come up through the soil under a home or building and enter through gaps and cracks in the foundation or insulation, as well as through pipes, drains, walls or other openings. Radon causes between 15,000 and 22,000 lung cancer deaths each year in the United States -- 12 percent of all lung cancer deaths are linked to radon. Because you cannot see or smell radon, the only way to tell if you are being exposed to the gas is by measuring radon levels. Exposure to radon in combination with cigarette smoking greatly increases the risk of lung cancer. That means for smokers, exposure to radon is an even greater health risk. Another leading cause of lung cancer is on-the-job exposure to cancer-causing substances or carcinogens. There are many different jobs that may involve exposure. Some examples are working with certain types of insulation, working in coke ovens, and repairing brakes. Lung cancer takes many years to develop. But changes in the lung can begin almost as soon as a person is exposed to cancer-causing substances. Soon after exposure begins, a few abnormal cells may appear in the lining of the bronchi, the main breathing tubes

Smoking cessation is the most important measure that can prevent lung cancer. Many products, such as nicotine gum, nicotine sprays, or nicotine inhalers, may be helpful to people trying to quit smoking. Using a home radon test kit can identify and allow correction of increased radon levels in the home, which can also cause lung cancers. Methods that allow early detection of cancers, such as the helical low-dose CT scan, may also be of value in the identification of small cancers that can be cured by surgical resection and prevention of widespread , incurable metastatic cancer.

The stage of a tumor refers to the extent to which a cancer has spread in the body. Staging involves both evaluation of a tumor's size as well as the presence or absence of metastases in the lymph nodes or in other organs. Staging is important for determining how a particular tumor should be treated, since lung cancer therapies are geared toward specific tumor stages. Staging of a tumor is also critical in estimating the prognosis of a given patient, with higher-stage tumors generally having a worse prognosis than lower-stage tumors. Doctors may use several tests to accurately stage a lung cancer, including laboratory blood chemistry tests, x-rays, CT scans, bone scans, and MRI scans. Abnormal blood chemistry tests may signal the presence of metastases in bone or liver, and radiological procedures can document the size of a tumor as well as possible spread to other organs.

Early lung cancer may not cause any symptoms. Many times, lung cancer is found when an x-ray is done for another reason. Symptoms may include a cough that doesn't go away, coughing up blood, shortness of breath, wheezing, chest pain, loss of appetite, losing weight