Bronchioloaveolar Carcinoma (BAC)

Lung adenocarcinoma has been increasing in recent years, whereas another form of non-small cell lung cancer, squamous cell carcinoma, has been decreasing. It is thought by some that the addition of filters to cigarettes allows smoke to be inhaled more deeply into the lungs where adenocarcinoma occurs.

Smoking is the most common cause of lung cancer overall, but many people diagnosed with adenocarcinoma of the lungs have never smoked. The most common cause in non-smokers is exposure to radon in the home. Lung adenocarcinoma is a multifactorial disease, meaning that several factors may work together to cause or prevent cancer.

Many environmental exposures can contribute to lung cancer risk in addition to smoking, and, like smoking, many of these are avoidable if we are aware of them. You can reduce your risk by doing things as simple as testing your home for radon and using an appropriate mask when working with certain chemicals. Some of the most common environmental causes of lung cancer include:

Radon

Exposure to radon in the home is the second-leading cause of lung cancer and the leading cause in non-smokers. Radon is a radioactive gas that is produced by the natural decay of uranium in the soil. It can enter homes through cracks in the foundation, around sump pumps and drains and through gaps around pipes and wires. Having been found in homes in all 50 states, the only way to know if you are safe is to test for radon. Simple do-it-yourself test kits are available at most hardware stores.

Asbestos

Exposure to asbestos is ordinarily considered an occupational exposure, but working with asbestos insulation in older homes (those built prior to 1970) can result in exposure too. Asbestos is responsible for roughly 84% of cases of mesothelioma, a cancer involving the lining of the lungs. Left alone, asbestos poses little danger, but exposure can result if it is disturbed. If you choose to remodel a home that may contain asbestos insulation, hire a certified contractor.

Air Pollution

Air pollution has been looked at as a possible risk factor for lung cancer, because there is a significant difference between the incidence of lung cancer in urban and rural areas, with lung cancer being more prevalent in urban areas. It is uncertain to what degree air pollution contributes to lung cancer in the United States, but according to the largest study to date, more than 10% of lung cancers in Europe may be secondary to air pollution.

Industrial Chemicals

As with asbestos, most exposures to cancer-causing chemicals occur in the workplace. Certain products used in the home, such as some wood strippers, contain chemicals that are associated with an increased risk of lung cancer. It is important to read labels on any of these products and take appropriate precautions as directed on the packaging.

Radiation Exposure

Exposure to medical radiation to the chest for other cancers, for example Hodgkin’s lymphoma or breast cancer, can increase the risk of lung cancer, although the benefits of treatment usually far outweigh this risk. In Japan, exposure to atomic bomb radiation was associated with an elevated risk of developing lung cancer.

Second-hand Smoke

Second-hand smoke increases the risk of lung cancer in an exposed nonsmoker two- to- three-fold times. It is currently felt to be responsible for 1.6% of lung cancers in the United States.

Occupational Causes of Lung Cancer

Occupation as a cause of lung cancer is common. It has been estimated that 13 to 29% of lung cancers in men are secondary to on-the-job exposure to chemicals and materials that increase the risk of lung cancer. Many of these exposures are preventable through awareness, and taking appropriate precautions. How Do I Know if Exposures at Work Can Raise My Risk?

Employers are required to provide Material Safety Data Sheets (MSDS’s) on chemicals you may be exposed to at the workplace. It is important to take the time to read these, and follow any safety recommendations that are suggested. That said, only 2% of chemicals used in commerce have been studied for carcinogenicity, that is their ability to cause cancer in humans. Though this is concerning, taking basic precautions could likely lower your risk considerably. When around chemicals, wearing gloves, ensuring proper ventilation, and using an appropriate mask are paramount. It is important to note that not all masks are created equally. Some exposures may be prevented with a simple dust mask, whereas others may require the use of a respirator to prevent a potentially toxic exposure.

The following lists of substances and occupations that could place you at risk is far from exhaustive, but provides an overview of some of the more common exposures that are linked with lung cancer.

 

Occupational Substances Associated With an Increased Risk of Lung Cancer:

Diesel fumes

Natural fibers – asbestos, silica, wood dust

Metals – aluminum, arsenic, beryllium, cadmium, chromium, nickel

Radon

Reactive chemicals – bis(chloromethyl) ether, mustard gas, vinyl chloride

Second-hand smoke

Solvents – benzene, toluene

Occupations Associated With an Increased Risk of Lung Cancer:

Asbestos workers

Bartenders

Ceramics

Chemists

Glass manufacturing

Painters

Printers

Masonry work

Metal work (iron and steel foundry work)

Sandblasting

Truck driving

Uranium mining

Genetics and Lung Cancer

It is well known that some cancers, such as ovarian cancer and colon cancer, run in families. Even though the role of heredity in lung cancer is not as well-known, having a family history of lung cancer does increase our risk to some degree. Hereditary lung cancer is higher in women, non-smokers and those with early onset lung cancer (lung cancer that occurs before the age of 60). Overall, it has been estimated that 1.7% of lung cancers up to the age of 68 are hereditary. Several factors are associated with hereditary lung cancer, including:

How Closely a Family Member is Related

Having a first-degree family member (parent, sibling or child) with lung cancer roughly doubles the risk of developing lung cancer. This risk is more for women and less for men and stronger in non-smokers than smokers. Having a second-degree relative (an aunt, uncle, niece or nephew) with lung cancer raises your risk by around 30%.

Smoking Status, Lung Cancer and Heredity

Smokers who develop lung cancer are less likely to have a family history than nonsmokers that develop lung cancer. That said, however, for those who have a genetic predisposition to lung cancer, smoking appears to amplify that risk.

Type of Lung Cancer and Heredity

Studies vary in the types of lung cancers that have the greatest hereditary component, but those with nonsmall cell lung cancers, especially lung adenocarcinoma are more likely to have a family history of lung cancer than those with small cell lung cancers.

A recent finding is that non-smokers with non-small cell lung cancer whose tumors have an EGFR mutation are much more likely to have a family history of lung cancer than those who have an ALK or KRAS mutation.

Race, Lung Cancer and Heredity

Blacks with first-degree relatives have a greater risk of early onset lung cancer than whites. This risk increases in smokers.

Other Cancers and Hereditary Lung Cancer

In general, having a family history of cancers other than lung cancer, does not appear to increase the risk that you will develop lung cancer. On the other side of the equation, though, those that develop more than one primary lung cancer are significantly more likely to have a genetic predisposition contributing to their cancer.