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What Causes Lung Cancer?

Lung cancer is a malignant disease in which the cells of the lung tissues become abnormal, characterized by uncontrollable, unlimited growth. As they grow, these abnormal cells can form tumors and interfere with the functioning of the lung. These lung cancer cells can then invade nearby tissue and destroy organ structure.

Lung Cancer Facts

Did You Know?

  • Lung cancer is the leading cause of cancer death and the second most common cancer among both men and women in America.
  • Each year, more people die of lung cancer than of colon, breast, and prostate cancers combined.
  • About two out of three people diagnosed with lung cancer are 65 or older.
  • Only one in every ten people with lung cancer are alive 5 years after diagnosis.

In order to understand more about lung cancer, it is important to understand the structure of the the lung and how it works.

The lungs are a pair of sponge shaped organ which located in the chest. Right lung has 3 lobes while left lung has 2 lobes, as shown in the picture below.

human lungs

Left lung is smaller than right lung because 2/3 of the heart is located on the left side of the body. The lungs bring air in and out of the body. They are taking in oxygen and remove carbon dioxide (respiratory residual substances).

Lining around the lungs called the Pleura, helps protect the lungs and allows them to move during breathing. Windpipe (trachea) brings air into the lungs. The trachea was divided into tubes called Bronchi, which then divided again into smaller branches called Bronchioles. At the end of these small branches are tiny air sacs called Alveoli.

Lung Cancer Causes and Risk Factors

In most case, lung cancer is caused by cigarette smoking. Even though some people who have never smoked may still get lung cancer, but statistics proved that about 90% of lung cancer patients were active smokers or former smokers.

These because tobacco contain over 4,000 chemicals, which 50 of them are known as carcinogens (cancer causing agents) that cause the actual damage to the cells in the lungs. A cell that is damaged may become cancerous in some period of time.

The risk of developing lung cancer increases with the number of cigarettes smoked especially if the person starts to smoke at a young age. The risk of developing lung cancer may be reduced slightly if you smoke filtered cigarettes, but it still far better if you are quit smoking.

Other Causes and Risk Factors for Lung Cancer

Exposure to Radon Gas

Radon is a radioactive gas that results from the natural breakdown of uranium in soil and rocks. In the outdoors, radon gas is diluted by fresh air, so it is not usually a concern. But radon can seep into buildings through dirt floors or cracks in the foundations. It may reach unsafe levels in enclosed, poorly ventilated spaces. Breathing in radon gas can damage cells that line the lungs.

According to the US Environmental Protection Agency (EPA), Radon is the leading cause of lung cancer in non-smokers and the second leading cause of lung cancer among smokers.

The risk of developing lung cancer depends on how much radon you are exposed to and how long you are exposed to it. The risk for lung cancer from radon is much higher in people who smoke than in those who don’t.

Family History

Your risk of lung cancer may be higher if your parents, siblings, or children have had lung cancer. This might be due to shared genes among family members and/ or they live in the same place where they are exposed to radon and other substances that can cause lung cancer.

Exposure to Asbestos

People exposed to large amounts of asbestos also have a greater risk of developing lung cancer. People who work with asbestos (such as in mines, mills, textile plants, and shipyards) are several times more likely to die of lung cancer. But, it’s not clear how much low-level or short-term exposure to asbestos might raise lung cancer risk.

Radiation Therapy to the Lungs

People who have had radiation therapy to the chest for other cancers are at higher risk for lung cancer, particularly if they smoke. Examples include people treated for Hodgkin disease or women who get radiation after a mastectomy for breast cancer.

Air Pollution

Air pollution is chemicals, particles and other materials in the air that could harm the health of humans, animals and plants.

There is strong evidence that exposure to outdoor air pollution causes lung cancer. The more air pollution you are exposed to, the greater your risk of developing lung cancer. These dangerous pollutants include benzene, diesel exhaust, particulate matter and some PAHs.

Poor Diet

Some studies show that people who eat a diet low in fruits and vegetables have a higher risk for lung cancer.

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