Smoking as a risk factor for lung cancer

It is well known that men are 7-10 times more likely to suffer from this deadly disease than women. From all types of cancer, lung cancer is now in the second place (for men), the first place being occupied by stomach cancer. With age, the risk of lung cancer is significantly increased, as the incidence in 60-69-year-old males is 60 times higher than in 30-year-olds.

A person may not be aware of the presence of this terrible disease for several years, and very often it is diagnosed too late, when doctors’ efforts are useless. Only 15% of lung cancer patients live for more than 5 years, while the rest die earlier.

Regardless of the quality of tobacco, the thickness of cigarettes or the filter, each cigarette contains at least 4.000 chemical compounds, while cigarette smoke — over 5.000, 60 of which cause cancer.

Scientists from all over the world have carried out numerous studies to determine the causes of cancer. At the moment, with absolute certainty, they are able to state that constant smoking causes cancer. Cigarettes contain lots of harmful carcinogens, most of which are stored in the last third of the smoked cigarette. As an effect of continuing smoking, these substances accumulate in the body, leading to the deformation of the structure and to the malfunction of the bronchial epithelium; thus, the columnar epithelium is replaced by stratified squamous epithelium. These changes ultimately lead to a quick development of malignant tumors.

Studies have shown that in 90% of cases, lung cancer is caused by smoking. A directly proportional relationship can be traced between the number of smoked cigarettes and the risk of cancer. Furthermore, smokers have a significantly higher probability of death.

A recent study by American scientists from Oregon State University for Research of Cancer has revealed how smoking is related to development of cancer. Under the influence of tobacco, smoke slows down the synthesis of the FANCD2 protein — a substance that protects the lungs from exposure to toxic substances. In this way, smoke poisons the said protein, which in turn changes the structure of DNA and, as a consequence, cancer occurs.

Smokers should be aware that they not only endanger their own lives, but also the lives of their loved ones. The role of passive smoking causing lung cancer has been proved. According to the statistics, members of a smoker’s family are 1.5-2 times more likely to develop cancer than members of a non-smoker’s family. Passive smoking is, in fact, the main cause of lung cancer in non-smokers. Recent studies have shown that the smoke exhaled by a smoker is more dangerous than that inhaled directly out of cigarettes. 10-15% of lung cancer patients have never smoked.

Over the past few decades, the number of lung cancer cases has increased exponentially. If 20 years ago, this terrible disease was experienced mainly by men, now women are increasingly developing malignant tumors. This is due to the fact that smoking is a very common harmful habit among the female population. Women who smoke and receive hormone therapy have a much higher risk of dying from lung cancer. It has been proven that women who take hormones are by 60% more likely to die from lung cancer than women taking a placebo. Among women who smoked (current and former smokers), 3.4% of those who took hormones died from lung cancer, compared to 2.3% of women taking placebos.

The likelihood of cancer occurrence depends on the duration and frequency of smoking. Chronic smokers are 20 times more likely to become victims of cancer than non-permanent smokers. Nowadays, however, an interesting trend seen is the decrease in the number of male smokers, and increase in the number of lung cancer patients. Many researches aiming to understand the link between smoking and cancer have concluded that the problem lies in the quality of the cigarettes. When smokers choose cheap cigarettes with no filter, they receive low-quality tobacco, its smoke containing huge amounts of carcinogens, which are the main cause of cancer.

After smoking, a radioactive substance called polonium remains on the bronchial epithelium. It is a known fact that radioactivity may cause accelerated and uncontrolled cell growth; however, it is still too early to say that it is an important cause of lung cancer.

The main cause of cancer in smokers may also be the presence of nicotine in cigarettes. When burned, it produces a substance — nicotine-nitrosamine — classified as a carcinogen. Tobacco smoke also contains other potentially hazardous substances: arsenic, nickel, cadmium and others.

Many smokers believe that the presence of a filter frees them from the ingestion of tar and other harmful substances. However, scientists have studied the safety of the filters. Accidental inhalation of fine threads, from which filters are made, may cause cancer.

1 kg of tobacco contains 70 ml of tobacco tar. Person smoking 1 kg of tobacco per month are passing 840 ml of tar per year through their airways and over 8 liters of tar across 10 years.

In order to attract more consumers, producers add all sorts of flavors and colors to their tobacco. New flavors and aromas attract new smokers, especially young girls, who tend to forget that smoking may cause cancer. Certainly, they do not even realize that the combustion of these substances emits very harmful chemicals.

Besides the above-mentioned substances contained in cigarettes, there are many other potentially hazardous components, such as nitrates, which ensure burning. Menthol cigarettes contain menthol. Pipe tobacco, in most cases, includes sugar and various flavoring agents. Scientists still cannot accurately determine the impact of all these substances on smokers’ health.

U.S. statistics reported that the arsenic content in different varieties of tobacco grown in the U.S.A has increased three times due to treatment of tobacco plantations with pest arsenical drugs. In all countries where tobacco products were imported from the United States, the death rate from cancer increased as rapidly as in the U.S.A. itself.

Another proven fact is that, when smoking cigars, a person inhales less and exhales more tobacco smoke, while when smoking cigarettes, almost all smoke is inhaled and thus the entire respiratory apparatus is exposed to tobacco smoke. This is supported by statistics which shows that lung cancer is much more common in cigarette smokers than in cigar smokers, while oral/mouth cancer is more common in cigar smokers.

Lung cancer mortality rate per 100,000 of population is expressed by the following: non-smokers — 3.4; smokers smoking less than half a pack of cigarettes per day — 51.4; persons smoking from half a pack to a pack per day — 144; more than 40 cigarettes per day — 217.

Lung cancer develops in about 20 years. Therefore, if the current number of smokers is so high, then, in 20 years, the number of patients with lung cancer will increase respectively.

If a person stops smoking, the chance of suffering from this deadly disease steadily decreases as the damaged lungs recover and contaminants are gradually removed. In addition, there is evidence that lung cancer in never-smokers has a better prognosis than in smokers; therefore, patients who smoke at the time of the diagnosis have a lower survival rate than those who have quit a long time ago.

Smoking is also the main cause of cancer in other organs, such as: the larynx, oral cavity, low lip, esophagus, bladder, kidneys and pancreas. Thus, quitting smoking is essential not only for healthy lungs, but also for the majority of organs and organ systems.

It is useless to intimidate smokers with warning labels on cigarette packs: very few people take them seriously, understanding that smokers were also among the people that contributed to their development. The following facts may provide smokers the motivation to quit smoking:

  • In only 3 to 6 months, chronic cough disappears and breathing becomes cleaner and smoother. Weakness disappears and sleep improves. Lung function increases by 10%.
  • After 5 months, lungs become clear of tar, tobacco dust and other harmful substances.
  • In the following year, the risk of coronary heart disease drops by 50%.
  • After 3-5 years, the risk of lung cancer drops to the level of non-smokers.
  • Quitting smoking is one of the most important and basic conditions for people, because as long as people are smoking, no external measures for cancer prevention will be truly effective. In conclusion, it’s never too late to quit smoking and to try leading a healthy lifestyle.

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