Lung cancer is the leading cause of cancer deaths worldwide. Responsible for 25% of all cancer deaths, lung cancer remains a topic of concern. According to the World Health Organization, each year, more people die of lung cancer than of colon, breast, and liver cancers combined. Worldwide, in 2020, there were 2.21 million new cases of lung cancer and 1.80 million deaths.
Risk Factors
Risk factors are things that increase the chances of a person developing a condition. However, they do not predict who will or will not develop a disease.
The main risk factors for lung cancer are: smoking tobacco, secondhand smoke, radon exposure, asbestos exposure, exposure to other cancer-causing substances, such as radioactive ores, arsenic, or diesel fumes, air pollution and a family history of lung cancer.
Tobacco Smoke
Cigarette smoking is the number one risk factor for lung cancer. In the United States, cigarette smoking is linked to about 80% to 90% of lung cancer deaths. Using other tobacco products such as cigars or pipes also increases the risk for lung cancer. Tobacco smoke is a toxic mix of more than 7,000 chemicals. Many are poisons. At least 70 are known to cause cancer in people or animals.
People who smoke cigarettes are 15 to 30 times more likely to get lung cancer or die from lung cancer than people who do not smoke. Even smoking a few cigarettes a day or smoking occasionally increases the risk of lung cancer. The more years a person smokes and the more cigarettes smoked each day, the more risk goes up.
People who quit smoking have a lower risk of lung cancer than if they had continued to smoke, but their risk is higher than the risk for people who never smoked. Quitting smoking at any age can lower the risk of lung cancer.
Secondhand Smoke Causes Lung Cancer
Secondhand smoke is a mix of two kinds of smoke: mainstream smoke -- what other people blow out after they take a puff and side stream smoke -- smoke that drifts from a burning cigarette or cigar. When you breathe it in, it’s called passive or involuntary smoking. You take in the same toxic chemicals the smoker does, just in smaller amounts. Even if you’re in a home or workplace with an air filter or open windows, if people are smoking, you can breathe it and get sick from it.
People who do not smoke but breathe in the smoke from others are also at an increased risk of lung cancer. Secondhand smoke is the third most common risk factor for lung cancer. Nonsmokers who are exposed to secondhand smoke at home or at work increase their risk of developing lung cancer by 20–30%. Secondhand smoke causes more than 7,300 lung cancer deaths among U.S. nonsmokers each year.
Even brief secondhand smoke exposure can damage cells in ways that set the cancer process in motion. As with active smoking, the longer the duration and the higher the level of exposure to secondhand smoke, the greater the risk of developing lung cancer.
Air Pollution
Air pollution occurs when harmful particles and gases enter the air people breathe. It is prevalent in urban and densely populated areas.
Outdoor air pollution causes roughly 1 in 10 cases of lung cancer. Smoking has a much bigger effect on the risk of developing lung cancer than air pollution.
There are a few different ways that particles in air pollution could damage DNA in cells and cause lung cancer. For example, tiny particles may build up in the lungs and change how cells replicate. This could lead to DNA damage which can cause cancer.
Indoor air pollution can have many sources. A key source of indoor air pollution is second-hand smoke from cigarettes. But burning of wood and coal to heat homes and cook with can also add to indoor air pollution.
Radiation Exposure
Several types of radiation exposure can increase the risk of lung cancer. Radon is one of the leading causes of lung cancer for people who do not smoke. Radon is the number one cause of lung cancer among non-smokers. Radon is a naturally occurring gas. Outside, it is unlikely to endanger people. Indoors, radon can be more concentrated. Long-term radon exposure indoors can lead to lung cancer. Lung cancer risk is higher for smokers due to synergistic effects of radon and cigarette smoking.
Radon is a naturally occurring radioactive gas which may be found in high concentrations in indoor environments, such as homes and workplaces. Radon is a radioactive gas that has no smell, colour or taste. Radon is produced from the natural radioactive decay of uranium, which is found in all rocks and soils. Radon can also be found in water.
Radon escapes from the ground into the air, where it decays and produces further radioactive particles. As we breathe, these particles are deposited on the cells lining the airways, where they can damage DNA and potentially cause lung cancer.
Outdoors, radon quickly dilutes to very low concentrations and is generally not a problem. Radon concentrations are higher indoors and in areas with minimal ventilation, with highest levels found in places like mines, caves and water treatment facilities
Radiation Therapy
People undergo radiation therapy as a treatment for cancer. However, radiation therapy on the chest can increase the risk for lung cancer. This could affect people undergoing radiation therapy for breast cancer, for example. In many cases, this risk is unavoidable, as the benefits of radiation therapy for people with other types of cancer typically outweigh the risks. Other sources of radiation people may come into contact with include radioactive ores, such as uranium.
Asbestos Exposure
Asbestos is a naturally occurring mineral that is carcinogenic, or cancer-causing. Before doctors understood its dangers, people used asbestos as a material in construction, car manufacturing, and industrial settings.Breathing in asbestos increases the risk of both lung cancer. The risk is especially high if a person becomes exposed to asbestos and also smokes.
A previous large study compared rates of lung cancer among insulation workers exposed to asbestos who smoked or didn’t smoked. The researchers found that people who smoked were 10 times more likely to develop cancer than nonsmokers. People exposed to asbestos were five times more likely to develop cancer than people not exposed. People who were exposed to asbestos and smoked were 50 times more likely to develop cancer than people not exposed to either risk factor.
Other Toxins
Other carcinogens may pose a risk for people who regularly come into contact with them. This may affect people who work with dangerous substances, such as: arsenic, cadmium, beryllium, silica, vinyl chloride, nickel compounds, chromium compounds, coal products, mustard gas and chloromethyl ethers.
Family History of Lung Cancer
Close family members of inpiduals diagnosed with lung cancer have a 50% higher risk of developing lung cancer themselves. This is true across sexes, races, and ethnicities, and it is not affected by other risk factors. People are also more likely to get lung cancer again if they have had it previously.
Tips to Reduce the Risk
There's no sure way to prevent lung cancer, but you can reduce your risk if you:don't smoke. If you've never smoked, don't start. Stop smoking. Stop smoking now. Quitting reduces your risk of lung cancer, even if you've smoked for years.
Avoid secondhand smoke. Avoid carcinogens at work. Take precautions to protect yourself from exposure to toxic chemicals at work. Follow your employer's precautions. For instance, if you're given a face mask for protection, always wear it.
Eat a diet full of fruits and vegetables. Choose a healthy diet with a variety of fruits and vegetables. Food sources of vitamins and nutrients are best. Avoid taking large doses of vitamins in pill form, as they may be harmful. For instance, researchers hoping to reduce the risk of lung cancer in heavy smokers gave them beta carotene supplements. Results showed the supplements actually increased the risk of cancer in smokers. Exercise most days of the week. If you don't exercise regularly, start out slowly. Try to exercise most days of the week.
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