Picture: Lung cancer affects the major organ of respiration - the lung and is the number one cause of cancer deaths in the world.
Lung Cancer

Lung Cancer

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Lung cancer facts

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  • Lung cancer is the number-one cause of cancer deaths in both men and women in the U.S. and worldwide.
  • Cigarette smoking is the principal risk factor for development of lung cancer.
  • Passive exposure to tobacco smoke also can cause lung cancer.
  • The two types of lung cancer, which grow and spread differently, are the small cell lung cancers (SCLC) and non-small cell lung cancers (NSCLC).
  • The stage of lung cancer refers to the extent to which the cancer has spread in the body.
  • Treatment of lung cancer can involve a combination of surgery, chemotherapy, and radiation therapy as well as newer experimental methods.
  • The general prognosis of lung cancer is poor, with overall survival rates of about 16% at five years.
  • Smoking cessation is the most important measure that can prevent the development of lung cancer.

What is lung cancer?

Cancer of the lung, like all cancers, results from an abnormality in the body's basic unit of life, the cell. Normally, the body maintains a system of checks and balances on cell growth so that cells divide to produce new cells only when new cells are needed. Disruption of this system of checks and balances on cell growth results in an uncontrolled division and proliferation of cells that eventually forms a mass known as a tumor.

Tumors can be benign or malignant; when we speak of "cancer," we are referring to those tumors that are malignant. Benign tumors usually can 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 and then 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 after it forms, 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.

The lung also is a very common site for metastasis from tumors in other parts of the body. Tumor metastases are made up of the same type of cells as the original (primary) tumor. For example, if prostate cancer spreads via the bloodstream to the lungs, it is metastatic prostate cancer in the lung and is not lung cancer.

The principal function of the lungs is to exchange gases between the air we breathe and the blood. Through the lung, carbon dioxide is removed from the bloodstream and oxygen from inspired air enters the bloodstream. The right lung has three lobes, while the left lung is divided into two lobes and a small structure called the lingula that is the equivalent of the middle lobe on the right. The major airways entering the lungs are the bronchi, which arise from the trachea. The bronchi branch into progressively smaller airways called bronchioles that end in tiny sacs known as alveoli where gas exchange occurs. The lungs and chest wall are covered with a thin layer of tissue called the pleura.

Lung cancer picture

Picture of lung cancer

Lung cancers can arise in any part of the lung, but 90%-95% of cancers of the lung are thought to arise from the epithelial cells, the cells lining the larger and smaller airways (bronchi and bronchioles); for this reason, lung cancers are sometimes called bronchogenic cancers or bronchogenic carcinomas. (Carcinoma is another term for cancer.) Cancers also can arise from the pleura (called mesotheliomas) or rarely from supporting tissues within the lungs, for example, the blood vessels.



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Lung Cancer Symptoms

When lung cancer first develops, there may be no symptoms at all. But as the cancer grows, it can cause changes that people should watch for. Common signs and symptoms of lung cancer include:

  • a cough that doesn't go away and gets worse over time
  • constant chest pain
  • coughing up blood
  • shortness of breath, wheezing, or hoarseness
  • repeated problems with pneumonia or bronchitis
  • swelling of the neck and face
  • loss of appetite or weight loss
  • fatigue.

These symptoms may be caused by lung cancer or by other conditions. It is important to check with a doctor if you have symptoms because only a doctor can make a diagnosis. Don't wait to feel pain. Early cancer usually doesn't cause pain.

SOURCE:
NIH Senior Health

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