The risk of developing lung cancer

 It is defined by the number of packs of cigarettes smoked per day multiplied by the number of years of addiction. For example, a person who has smoked two packs a day for 10 years has a smoking history of 20 pack / year.

Although the risk of developing lung cancer increase even with a history of 10 pack / year, those with a history of 30 pack / year or more are considered the most at risk of developing lung cancer.
 Among those who smoke two or more packs of cigarettes per day, one in seven will die of lung cancer.
Cigars or pipes can also cause lung cancer, although the risk is not as high as the cigarette
While someone who smokes only one pack of cigarettes a day run a risk of developing lung 25 times higher than a nonsmoker cancer, those who smoke cigars and cigarettes runs a 5-fold increased risk.
Tobacco smoke contains over 4000 chemical compounds, many of which have been shown to cause cancer.
The two primary carcinogens in tobacco smoke are chemicals known as nitrosamines and polycyclic aromatic hydrocarbons.

The risk of lung cancer decreases each year following smoking cessation as normal cells grow and replace damaged cells in the lung.

In former smokers, the risk of developing cancer begins to be the same as a nonsmoker about 15 years after smoking cessation.

 Passive smoking Passive smoking or the inhalation of tobacco smoke from other smokers who live or work with a person is also a risk factor for lung cancer. Research has shown that nonsmokers who reside with a smoker have a 24% increase in the risk of developing lung cancer when compared with other nonsmokers.