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Tobacco as a cause of lung cancer

Over the last sixty years, doctors, scientists and clinical researchers have established what many observers have long felt was the case: a causal link exists between smoking cigarettes and the incidence of lung cancer. Lung cancer occurs when the cells within the lung tissue are altered at a genetic level to mutate and multiply at an aggressive rate.

The results of many studies on the effects of tobacco have shown that cigarette smoke carries numerous chemicals, called “mutagens”, that cause lung tissue cells to mutate. Substances such as carbon monoxide, hydrogen peroxide and benzopyrene contained in cigarette smoke affect how cells change and grow.

One of the earliest studies into the relationship between smoking and lung cancer came from the School of Medicine at Washington University in St. Louis. Ernst Wynder, a first-year medical school student, started the first research efforts into the causes of lung cancer in 1948. He examined the cadaver of a man who had died of lung cancer to find that the lungs were blackened. Two years later, he published a study that showed that lung cancer rates were as much as forty times higher in smokers than non-smokers.

Although the link between cigarette smoke and cancer has been understood for decades, the so-called “smoking gun” came to light in 1998. Researchers found out how benzopyrene affects a gene known as “p53”. The gene acts as a screening agent to make sure that healthy cells divide while unhealthy ones die off. In the cases of cigarette smokers, benzopyrene “shuts off” the p53 mechanism, allowing unhealthy and malignant cells to grow and spread throughout the body.

The statistics surrounding the link between cigarette smoking and lung cancer show some startling truths. According to studies conducted by major life insurance firms, the act of smoking a single cigarette can shorten the smoker’s life by ten minutes. By this measure, each pack shortens a smoker’s life expectancy by 3.5 hours. For a two-pack-a-day smoker, that adds up to more than one hundred days per year of reduced life expectancy – more than twenty-eight percent. Over 80 percent of lung cancer cases are attributable to cigarette smoking. Twenty percent of all deaths in the US are tobacco-related.

Smoking in combination with exposure to other carcinogens can raise the risk of lung cancer. Studies have shown that people who were exposed to asbestos fibers in the workplace and who smoke can have over 40 times the risk for developing lung cancer as those who smoke and do not have significant asbestos exposure.

Benefits to Quitting Smoking
Time After Quitting Benefit
20 minutes Heart rate and blood pressure drop
12 hours Carbon monoxide level in the blood drops to normal
2 weeks to 3 months Circulation improves and lung function increases
1 to 9 months Coughing and shortness of breath decrease; cilia (hair-like structures that move mucus out of the lungs) start to regain normal function in the lungs, increasing the ability to handle mucus, clean the lungs and reduce the risk of infection
1 year Excess risk of coronary heart disease is half that of a continuing smoker
5 years Risk of cancer of the mouth, throat, esophagus and bladder are cut in half; cervical cancer risk falls to that of a non-smoker; stroke risk can fall to that of a non-smoker after 2 to 5 years
10 years Risk of dying from lung cancer is about half that of a person who is still smoking; risk of cancer of the larynx and pancreas decreases
15 years Risk of coronary heart disease is that of a non-smoker’s

Smoking and Vulnerability to Disease


Smoking And Lung Cancer

Smoking is the major cause of lung cancer. However, what many people do not realize is that smoking often is not necessarily the cause, but instead the enabler.

Cigarette smoking weakens the lungs and decreases their ability to expel fibers. It's this weakness of the lungs that leave people vulnerable to other carcinogens. Many people are exposed to dangerous materials in a work or home environment, often without their knowledge. And even though these other carcinogens may have been causes of the lung cancer the weakened lung was more susceptible to being attacked.

Not only does exposure to smoke weaken the lungs, it also irritates the air passages causing a higher production of mucus. With more mucus in the air passages, the passage of air is restricted which further decreases the removal of dangerous fibers from the lungs.

Rhadon and asbestos are the two most serious carcinogens that become that much more dangerous when they get in a weaker lung. More of the chemical or fiber stay in the lung ultimately leading to a much higher likelihood of cancer when these products are combined with someone exposed to smoke.

It is extremely difficult to tell which of many exposures, from cigarette smoke, to ambient air pollution, caused someone's lung cancer. However, it is important to identify a number of the possible causes because it can significantly affect someone's financial options.

Read more about:
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Smoking and Increased Vulnerability to Disease
»Cancer Risk from Smoking and Asbestos Exposure
»Cancer Risk from Smoking and Radon Exposure
»Lung Cancer Screening
»Lung Cancer Diagnosis