Causes of Lung Cancer

Lung cancer occurs when abnormal cells grow uncontrollably in the lungs, evading the immune system and not dying off as they normally should. As a result, these cells can form tumors in the lungs. Numerous factors have been identified that may contribute to the development of lung cancer, including the following:

Genetic Changes

The development of cancer is often linked to alterations in various genes. In such cases, lung cancer may be more prevalent among younger individuals. These genetic changes can either be inherited or acquired:

Inherited Genetic Changes: Some individuals may inherit mutations or genetic changes from their parents, significantly increasing their risk of developing lung cancer.
Acquired Genetic Changes: These mutations can occur during an individual’s lifetime due to exposure to environmental factors such as the chemicals found in tobacco smoke. However, some genetic changes arise randomly within cells without any external causes. In truth, the genetic alterations that lead to lung cancer are typically acquired.

Smoking

Smoking remains the leading cause of lung cancer in most cases, which includes both smokers and those exposed to secondhand smoke. Tobacco smoke contains numerous carcinogenic substances, and when a person starts smoking, immediate changes begin to occur in the lung tissue. Initially, the body is able to repair this damage on its own, but with continuous smoking, the damaged cells in the lung lining accumulate. Over time, these cells may behave abnormally, ultimately resulting in cancer. The risk of developing lung cancer correlates with the number of cigarettes smoked and the duration of smoking. Notably, the risk decreases after quitting smoking, yet former smokers retain a higher risk compared to those who have never smoked. Additionally, secondhand smoke increases lung cancer risk, even for non-smokers.

Tobacco Smoke

While cigarette smoking presents the greatest risk factor for lung cancer, the use of other tobacco products can also elevate the chances of developing lung cancer, along with various other cancers, such as cancers of the mouth and esophagus. Examples of other tobacco products include:

Cigars
Pipes
Snuff
Chewing tobacco

Marijuana Smoke

Smoking marijuana also increases the risk of lung cancer, as it contains carcinogens. Many marijuana users tend to mix it with tobacco, and although this results in less tobacco consumption compared to traditional cigarette smokers, they often inhale more deeply and hold the smoke in their lungs longer. Consequently, it is estimated that smoking four marijuana-and-tobacco cigarettes can cause damage equivalent to smoking 20 traditional cigarettes. Even smoking marijuana alone poses similar risks and can contribute to lung cancer and severe health complications.

Electronic Cigarettes

The risk of lung cancer associated with electronic cigarettes is still under investigation; however, many researchers believe that these devices could potentially cause lung cancer. This belief stems from the understanding that lung cancer related to traditional cigarettes is due to small particles left by nicotine in the lungs, particularly in the airways, and the same phenomenon is expected in electronic cigarette usage.

Risk Factors for Lung Cancer

Certain risk factors are controllable, such as quitting smoking, while others, like family medical history, are not. It is crucial to note that possessing a risk factor does not guarantee the onset of lung cancer, and conversely, a lack of risk factors does not ensure one will not develop it. Below are some risk factors that may contribute to the development of lung cancer:

Radon Gas Exposure

Exposure to radon gas significantly increases the risk of lung cancer and is considered the leading cause of lung cancer in non-smokers. Among smokers, it ranks as the second leading cause after smoking itself. Radon is a colorless, odorless gas produced by the natural decay of uranium in soil and rock. Outdoor air typically dilutes radon’s concentration, making it less concerning; however, it can seep into buildings through dirt floors or cracks in foundations, potentially reaching unsafe levels in enclosed or poorly ventilated spaces. In terms of lung cancer, radon can damage lung lining cells, and the risk depends on both the quantity of radon exposure and the duration of that exposure, with smokers being at a higher risk.

Personal or Family Medical History

Individuals who have previously experienced lung cancer may face an increased risk of developing it again, particularly those who smoke. Moreover, a family history of lung cancer, such as a parent, sibling, or child having the disease, may also elevate the risk. This could be due to shared smoking habits or exposure to environmental risk factors, such as radon, in their homes or workplaces. It’s important to note that most lung cancer cases do not run in families, though individuals with a history of cancers such as oral or throat cancer may also have a higher risk of lung cancer.

Exposure to Certain Substances and Chemicals

Long-term exposure to specific substances and chemicals can increase the likelihood of developing lung cancer. For instance, prolonged exposure to diesel exhaust over several years may elevate the risk, as can living in areas with high concentrations of nitrogen oxides, often emitted from automobiles. Additionally, various industrial substances and chemicals can heighten the risk of lung cancer, including:

Arsenic
Beryllium
Cadmium
Silica
Nickel
Coal smoke and coke
Asbestos

Weakened Immune System

Infection with HIV, the virus that causes AIDS, can weaken the immune system, putting individuals at greater risk for certain cancers, including lung cancer. Likewise, individuals on immunosuppressant medications, commonly prescribed after organ transplants, also have an elevated risk of developing lung cancer.

Air Pollution

There is substantial evidence that exposure to air pollution and its components can result in lung cancer. Increased exposure to air pollution correlates with a heightened risk of lung cancer. Air pollution consists of chemicals, particles, and other materials in the air at levels that may harm health or the environment. Pollutants can include diesel and gasoline emissions, as well as polycyclic aromatic hydrocarbons. These pollutants may vary by location due to different emission sources and can be carried from one area to another.

Other Risk Factors

In addition to the previously mentioned factors, several other variables can also heighten the risk of lung cancer, including:

Previous radiation exposure: Undergoing radiation therapy in the chest area for another type of cancer can increase the risk of lung cancer. However, it is crucial to understand that the benefits of radiation therapy outweigh any potential risks when prescribed by a qualified physician.
Age: Lung cancer is commonly diagnosed in individuals aged 60 and above, although it can occur at a younger age. The average age at diagnosis is 71.
Gender: Men are generally more susceptible to lung cancer compared to women.
Race: African American men face a higher risk of lung cancer than men from other racial groups.
Pre-existing lung diseases or conditions leading to scarring: Various conditions can increase the likelihood of lung cancer, including:
- Chronic Obstructive Pulmonary Disease (COPD), typically caused by smoking, which results in chronic lung damage.
- Emphysema and chronic bronchitis, both of which are forms of COPD.
- Lung infections, including those caused by Chlamydophila pneumoniae or tuberculosis.
Lupus: Individuals with systemic lupus erythematosus, an autoimmune disease, may experience lung inflammation, increasing their risk of developing lung cancer.
Beta Carotene Supplements: Studies indicate that taking beta carotene supplements may elevate the risk of lung cancer, particularly among smokers.