What is lung cancer?

Lung cancer starts in the lung cells and may potentially spread to the lymph nodes or other organs in the body.
Lung cancer starts in the lung cells and may potentially spread to the lymph nodes or other organs in the body.

Lung cancer is cancer that originates in the lung cells.

Cancer is an abnormal and uncontrolled growth of the cells in the body. These abnormal cells kill the normal cells of the body and disrupt the normal body functions.

Lung cancer may spread to the lymph nodes or other organs in the body that commonly include the liver, bones, brain, and adrenal glands. When cancer cells spread from one organ to another, it is called metastasis.

According to the American Cancer Society, lung cancer is one of the top 10 leading causes of cancer deaths globally. People dying from lung cancer alone are more than those dying from colon, breast, and prostate cancers combined. 

However, early detection and advanced treatment options are a ray of hope for patients with lung cancer.

What is usually the first sign of lung cancer?

Most often, lung cancer does not show any signs and symptoms until it has advanced to higher stages when it becomes difficult to treat. The initial signs and symptoms vary among patients but may include the following:

What puts you at risk for lung cancer?

Cigarette smoking is the leading cause of lung cancer. Inhalation of tobacco smoke by non-smokers (passive smoking) is the next factor that can lead to cancer. 

As many as 90% of lung cancer diagnoses could be prevented if there is no more cigarette smoking. Among people who smoke two or more packs of cigarettes/day, one in seven will die of lung cancer. 

Other risk factors for lung cancer include the following:

What are the four stages of lung cancer?

The four stages of lung cancer (based on a grading system) are known as TNM classification. The TNM grades have been derived from diagnostic tests such as

  • blood tests,
  • computed tomography (CT) scans,
  • bronchoscopy,
  • positron emission tomography (PET) scans, etc.

Knowing the stage of the lung cancer helps the oncologist select the right treatment.

In the increasing order of severity, the stages of lung cancer are as follows:

  • Stage 0: This stage describes cancer in situ, which means “in place.” Stage 0 cancers are still located in the place they started and do not spread to the nearby tissues. This stage of cancer is often highly curable, usually by removing the entire tumor with surgery.
  • Stage I: This stage is usually a small tumor that has not grown deeply into the nearby tissues. It is often called early-stage cancer.
  • Stages II and III: At these two stages, lung cancer has grown more deeply into its adjacent tissues. Lung cancer may have spread to the lymph nodes.
  • Stage IV: This stage means that lung cancer has spread or metastasized in other organs. This is usually known as the advanced stage of lung cancer.


Lung cancer is a disease in which lung cells grow abnormally in an uncontrolled way. See Answer

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