common cause of lung cancer

Lung cancer is the leading cause of cancer deaths in both men and women worldwide. The American Cancer Society estimates that 222,520 new cases of lung cancer in the United States will be diagnosed and 157,300 deaths from lung cancer will occur in 2010. The U.S. National Cancer Institute, approximately one out of every 14 men and women in the U.S. will be diagnosed with lung cancer at some point in their lives.

Lung cancer is predominantly a disease of older people, nearly 70% of people diagnosed with lung cancer in 65 years, while less than 3% of lung cancers occur in people under 45 years.

Lung cancer is uncommon before 1930, but rose dramatically during the following decades as tobacco smoking increased. In many developing countries, the incidence of lung cancer began to decline after public education about the dangers of smoking and the use of effective cessation programs. But lung cancer is still among the most common form of cancer in men and women worldwide. In the U.S., lung cancer surpassed breast cancer as the most common cause of cancer deaths in women.

What causes cancer?

Smoke

The incidence of lung cancer associated with smoking, with around 90% of lung cancers that arise from the use of tobacco. Risk of lung cancer increases with the number of cigarettes smoked and the time where smoking has occurred, doctors see these risks in packets-year history of smoking (number of packs of cigarettes smoked per day multiplied by the number of years smoking). For example, as someone has smoked two packs of cigarettes a day for 10 years had smoked 20 pack-year history. While the risk of lung cancer increases, even with a history of smoking 10-pack-years, are people with a history of 30 pack-years or more is considered to be at highest risk of developing lung cancer. Among those who smoked two or more packs of cigarettes a day, one in seven will die of lung cancer.

Cigar and pipe smoking can also cause lung cancer, although the risk is not as high as with smoking. So while someone who smoked a pack of cigarettes a day had a risk of developing lung cancer is 25 times higher than non-smokers, pipe and cigar smokers have an increased risk of lung cancer is about five times greater than non-smokers.

Tobacco smoke contains over 4,000 chemical compounds, many of which have been shown to cause cancer or carcinogenic. Two major carcinogens in tobacco smoke are chemicals known as nitrosamines and polycyclic aromatic hydrocarbons. The risk of lung cancer decreases each year after cessation of smoking as normal cells grow and replace damaged cells in the lungs. In former smokers approach to the risk of lung cancer from nonsmokers about 15 years after quitting.

Passive smoking

passive smoking or inhaling smoke from smokers who share a residence or work permit with smokers, is also a risk factor that made for the development of lung cancer. Research has shown that nonsmokers who live with smokers have a 24% increase in risk of lung cancer compared with smokers who do not live with a smoker. It is estimated that 3000 deaths from lung cancer occur each year in the U.S. as a result of passive smoking.

Asbestos fibers

asbestos fibers, silica fibers, which can hold a lifetime in the lung tissue after exposure to asbestos. The workplace is a common source of exposure to asbestos fibers, asbestos was widely used in the past both as heat and sound insulation. Currently, the use of asbestos is restricted or prohibited in many countries including the U.S. Both lung cancer and mesothelioma (cancer of the lungs and pleura, the lining of the abdominal cavity called the peritoneum) is associated with exposure to asbestos. Cigarette smoking drastically increases the chance of developing lung cancer associated with asbestos workers exposed to asbestos. Asbestos workers who smoke have a risk five times higher lung cancer than nonsmokers, but asbestos workers who smoke have a risk of fifty to ninetyfold larger than non-smokers.

Radon gas

Radon gas is a gas, an inert chemical nature, which is a natural decay product of uranium. Uranium decays to form products, including radon, which has issued a type of ionizing radiation. Radon is a gas known to cause lung cancer, with an estimated 12% of lung cancer deaths from radon, or about 20,000 lung cancer deaths associated each year in the U.S., making radon the second leading cause of lung cancer in the U.S. As with exposure to asbestos as smoking increases the risk of lung cancer with radon exposure. Radon can travel through soil and into homes through foundation cracks, pipes, ducts or other openings. U.S. Environmental Protection Agency estimates that one in every 15 homes in the U.S. contains dangerous levels of radon. Radon is invisible and odorless, but can be detected with simple test kits.

Tend to the family

While the majority of lung cancer related to smoking, the fact that not all smokers eventually suffer from lung cancer suggests that other factors such as individual genetic susceptibility may play a role in the cause of lung cancer. Numerous studies have shown that lung cancer is more likely to occur in both smoking and nonsmoking relatives of those who have been suffering from lung cancer than the general population. Recently, the largest genetic study of lung cancer ever conducted, involving more than 10,000 people from 18 countries and chaired by the International Agency for Research on Cancer (IARC) identified a small region in the (DNA) genome that contains genes seems to give an increased susceptibility to lung cancer in smokers. Specific gene, which lies q arm of chromosome 15, coding for proteins that interact with nicotine and other tobacco toxins (nicotinic acetylcholine receptor gene).

Lung Disease

The presence of certain diseases of the lungs, particularly chronic obstructive pulmonary disease (COPD) is associated with increased risk (05:56 times greater risk of non-smokers) for lung cancer development even after the effects of smoking at the same time is excluded.

History of lung cancer

Congratulations from lung cancer have a higher risk of both lung cancer than the general population had developed lung cancer at first. Cancer survivors from non-small cell lung cancers (NSCLCs, see below) has an additive risk of 1% -2% a year to develop a second lung cancer. In survivors of small cell lung cancer (SCLCs, see below), the risk of developing lung cancer both approaches 6% annually.

Air Pollution

Air pollution from vehicles, industry and power stations, increasing the chances of developing lung cancer in people who are affected. Up to 1% of lung cancer deaths from breathing polluted air, and experts believe that prolonged exposure to highly polluted air can carry the risk of developing lung cancer similar to passive smoking.