What are the risk factors for developing lung cancer?

Risk factors for developing lung cancer include exposure to toxic substances and genetic predisposition.

What is lung cancer?

Lung cancer is a cancer that develops due to uncontrolled cell division of abnormal cells in the lungs.

Normally, the DNA in a cell directs how fast the cell grows, when it should divide, and when it should die. In cancer cells, mutations in their DNA lead to uncontrolled growth and division making masses of cells called tumors. The cancer cells also do not die like normal cells. The tumors get bigger and can grow into healthy tissues and damage them. The cancer cells can also break away and spread out to other parts of the body and start the formation of new tumors on those sites.

Lung cancer is often detected in advanced stages which makes it harder to control. According to WHO, lung cancer is a leading cause of cancer-related deaths worldwide affecting both men and women. Approximately 127,070 people in the United States, and 1.8 million people worldwide die of lung cancer each year. In the US, lung cancer kills 3 times more men than prostate cancer, and 3 times more women than breast cancer.

What causes lung cancer

Any substance that can interact with the DNA of healthy cells and cause mutations can cause cancer. Such substances are said to be carcinogenic. Carcinogenic contaminants (carcinogens) in the air we breathe can reach the lungs and mutate the cells there causing cancer. Some mutations may also be inherited in one’s DNA leading to a family history of lung cancer or other cancers.

Risk factors for developing lung cancer

1. Smoking tobacco

Tobacco smoking is the single biggest cause of lung cancer worldwide. According to WHO, 85% of all lung cancers are caused by smoking. It is also estimated that 90% of all lung cancer diagnoses could be prevented if cigarette smoking was eliminated.

Tobacco smoke has thousands of compounds in it including over well-established carcinogens. Each puff of a cigarette exposes the mouth, throat, esophagus, lungs, and other parts of the body to carcinogens that could mutate healthy cells into cancer cells. In addition to lung cancer, tobacco smoke is known to cause cancers in the oral cavity, larynx, pharynx, esophagus, stomach, kidney, bladder, pancreas, and cervix. It can also cause acute myeloid leukemia.

The more the toxic substances of tobacco smoke are inhaled, the greater their exposure to inner organs and the greater their chance of causing cancer. Mild exposure such as that through secondhand smoke (being in the presence of others smoking) can cause cancer. The likelihood of cancer increases with firsthand smoking and goes higher with the duration of smoking and the number of instances of smoking.

2. Exposure to radon gas

Radon gas is a carcinogenic gas that is found in areas with a high uranium content in the soil. It is also released into the air by some building materials. While exposure to radon gas in the outside air is negligible, radon gas levels can build up inside a house exposing those who live there. Exposure to radon gas is the major cause of lung cancer in non-smokers and accounts for about 21,000 deaths by lung cancer in the US annually.

3. Occupational hazards

Exposure to carcinogenic chemicals at work can cause lung cancer. These chemicals include:

• Uranium ores or other radioactive ores.
• Inhaled chemicals which include compounds such as vinyl chloride and formaldehyde (which can emanate during manufacturing and installation of vinyl floors), arsenic (used in the production of semiconductors, electronics, etc.), cadmium (used in batteries, solar cells, etc.), silica (used in glass manufacturing), and chloromethyl ethers (used in making plastics, treating textiles, etc.).
• Diesel fumes, tar, and soot released from burning fossil fuels.
• Asbestos, a carcinogen associated with several cancers including lung cancer. The chemical was used in the 1960s and 1970s when people who worked in mines, mills, textile plants, and places where insulation was used came in contact with it. In the U.S. currently, people come in contact with asbestos when repairing, renovating, maintaining, or tearing down older structures with asbestos in them.

4. Previous radiation therapy

Radiation therapy given as a part of the treatment for some other cancers can increase the chances of developing lung cancer.