Lung Cancer Due To Cigarette Smoking
It is believed that tobacco plant is native to America and started to be grown as early as 6000 B.C. Since antiquity to the present though the origin of the plant is enigmatic, historical records say that Columbus introduced this plant to Europe. Tobacco showed its presence in France in 1556 and in UK in 1565. Also history records of its commercial cultivation in Virginia and other parts of United States since the 17th century.
Lung cancer has been known, amongst people exposed to industrial fumes, since the beginning of late 19th century and acquired predominance in the western world during the early 90s. This was the era of 'Industrial Revolution'. It was first common in men but near historical trends tend to reverse the scenario with highest increase incidence rate among the women. If these trends continue women would be having higher prevalence in the near future. World Health Organization reports an increase in 76% death rates in men and 135% the same rates in women, thus making lung cancer the most common cancer in the world. Globally 85% in men and 46% in women of the lung cancer rates are due to smoking alone.
The tobacco revolution.
Lung cancer still remains low in the underdeveloped nations where smoking is less widely adopted as a way of life. Tobacco revolution began in Europe and consequently in Americas. It was one of the single major reasons for very high increased rate of lung cancers in the western world. This is very much proved by statistics in Poland where use of cigarette has been earlier and hence the consecutive high lung cancer rate.
Magnitude of the problem
In terms of incidence the most common cancer is lung cancer as per world statistics. 1.1 million Deaths occur annually due to lung cancer which is nearly twice the rates for breast cancer which is the second largest cause of cancer. 28% of all cancer deaths are due to lung cancer. About one third of the adults globally smoke. Every eighth second somebody dies of tobacco smoke. About 10 million cigarettes are sold per minute accounting for nearly15 billion cigarettes sold every day (WHO).
An estimated, 20.8% of all adults (45.3 million people) smoke cigarettes in the United States. Lung cancer is the most common cause of death in the US, with nearly 124,000 deaths in 2001. More than 400,000 people die in the US, due to diseases associated with smoking, and it accounts for one out of every five deaths. Nearly 40% of smokers die in smoke related health problems.
Health effects of smoking
Health risks of smoking
Cigarette smoking affects almost all the systems of the body. It mainly affects the respiratory system, cardiovascular system, gastrointestinal system and the central nervous system though minor problems associated with genitor-urinary system have been reported.
Cigarette smoking can cause malignancies of various organs like lung, oral cavity, uterine cervix, urinary bladder, ureter, liver, nasopharynx, esophagus, stomach, pancreas, paranasal sinus, hypopharynx and hemopoetic system (myeloid leukemia). Alcohol has a synergistic action on cigarette smoke in causing cancer of oral cavity, esophagus and lungs.
Epidemiological data have strongly indicated the relation between smoking and lung cancer. This has been associated to FHIT (Fragile Histidine Triad) gene on chromosome 3p14.2 alterations as proved by recent studies. FHIT gene is the prime target of carcinogens and many studies have proved irreversible mutation in this gene, there by leading to lung cancer.
Other gene that has been implicated is p53 gene on chromosome 17, which is a prime tumor suppressor genes. Many studies in Japan have proved the direct association between smoking and p53 mutations, Non-small cell cancers being the most common consequence.
Adenocarcinoma of lung once considered minimally related to cigarette smoking now has been proved to be the reverse, as observed by the cancer prevention studies and certain other antecedent studies.
Effects on Heart
Smoking releases several toxic hydrocarbons like CO and other cyclines which induce atherogenesis. Nicotine stimulation elevates blood pressure and myocardial oxygen demand. Also in some studies there is a reversal of lipid profile with fall in protective HDL. Calculated risk includes 25% of CHD deaths, less than 65 years due to smoking, the degree of risk being even higher in men under 50 years of age. Thus CHDs have a direct association with the cigarettes per day. Filtered cigarettes offer no protection against CHDs. There is a synergistic association between smoking and other atherosclerotic factors, there by increasing the risk of coronary heart diseases. Nearly 90% of the peripheral vascular diseases in non-diabetics are attributed to cigarette smoking.
As described above smoking can cause various carcinomas of gastrointestinal system. This including cancer of esophagus, oral cavity, stomach, pancreas and liver. Although smoking has a protective effect on ulcerative colitis it is known to cause Crohn's disease. Studies show that smoking can disrupt the colonic mucosal function and reduce the rectal blood flow by the vasoconstrictive action of nicotine. Some amount of inhaled gas will reach stomach and this can lead to gastritis and will delay the healing of peptic ulcer as well.
Somatic and psychological system
Nicotine is the prime chemical present in cigarettes and it is malicious largely because of its physical additive properties. Smokers have physical dependence to adjust their Nicotine blood levels and they achieve this by increasing the amount of nicotine intake. This is achieved through increasing their number and frequency of smoking. Smokers need to maintain a steady level of nicotine in their blood to get psychoactive effect and to avoid withdrawal symptoms. Nicotine increases the activation of dopaminergic receptors in the brain. Harmane which is a MAO inhibitor formed from acetaldehyde, present in cigarette smoke, facilitates nicotine addiction.
Passive smoking or second hand smoking is a condition where exhaled smoke by a cigarette smoker and smoke directly from the tip of cigarette is inhaled by people who are near to the smoker. The former is called 'mainstream smoking' and the latter 'side stream smoking'. Passive smoking is as risky as active smoking in causing lung cancer as has been proved by many studies which include the study by S. A. Gland and W. W. Parmley. But surprisingly cardiovascular risk factors are less frequent in association, when compared to the association between lung cancer and passive smoking.
Deaths from Passive Smoking
Total Deaths: 53,000
Pie chart of US deaths from environmental tobacco smoke. The majority of annual deaths are attributed to heart disease.
(SA Glantz, S. A., Parmley, W. W. (1991). Passive smoking and heart disease. Epidemiology, physiology, and biochemistry. Circulation. 83: 1-12.)
Health effects of passive smoking
Passive smoking mainly affects infants and young children than adults. In infants and children it is known to cause SIADH, acute severe attack of asthma, dental caries and it can also impede the growth of lung. In adults passive smoking can cause heart diseases and respiratory problems like chronic bronchitis, emphysema and asthma. It can also cause lung cancer.
Health benefits of smoking
Nicotine present in cigarette is protective to some diseases like Parkinsonism and Alzheimer's diseases. Cigarette smoking can also ameliorate Tourette's syndrome. All these effects are due to the protective action of Nicotine on Dopamine. Nicotine inhibits MAO activity which breaks down Dopamine.
Studies also show that anti-estrogenic effect of cigarette smoking has a beneficial effect on Uterine fibroid, Endometriosis, Hyperemesis gravidarum and hypertensive disorders of pregnancy including pre-eclampsia and eclampsia. Risk of uterine cancer in post menopausal women is lower in those who smoke.
Cigarette smoking can also alter the PG pathway and this action can recuperate chronic inflammatory diseases like Ulcerative colitis and extrinsic allergic alveolitis like Farmer's lung.
Carcinogenic chemicals in cigarettes
According to International Agency for Research on Cancer, there are around 4700 chemicals in cigarette and more than 60 are known to be carcinogenic in humans. Forty-three of the more than 4,700 chemical compounds contained in cigarette smoke are known carcinogens (US Environmental Protection Agency and US Consumer Product Safety Commission 1995). Though the leaves of tobacco harbor many carcinogenic chemicals, incineration and smoking produces nearly hundreds of many more toxic carcinogenic chemicals. Following are some of the chemical carcinogens produced by cigarette smoke.
"Tar", also known as total particulate matter, is inhaled when the smoker draws in, on a lighted cigarette. It contains aerosolized particulate matter except nicotine and moisture. In its condensate form, tar is the sticky brown substance which can stain smokers' fingers and teeth yellow-brown.
Arsenic mainly affects central nervous system, cardiovascular system and gastrointestinal system. Chronic arsenic poisoning can lead to Diabetes mellitus, vasospasm, gangrene of legs, peripheral neuropathy and cancers affecting skin, liver, lung, bladder, kidney etc.
Polonium is a rare radioactive material emitting alpha radiations. Po-210 is the commonest form of the element found in the nature. It has a radiological half life of 138.4 and biological half life of 60 days. It gets accumulated in the spleen and liver, damaging those organs and is highly carcinogenic. Alexander Litvinenko, a former KGB (former USSR secret service) agent was killed in 2006 by exposure to Po-210 in London. He is the first known lethal victim of Po - 210 poisoning.
4. Polycyclic aromatic hydrocarbons.
The chief polycyclic aromatic hydrocarbons present in cigarette smoke are Benzo[a]pyrene, Benzo[b]fluoranthane, Benzo[j]fluoranthane, Benzo[k]fluoranthane, Dibenzo[a,i]pyrene, Indeno[1,2,3-cd]pyrene and Dibenz[a,h]anthracene. PAH is found in cigarette and is released when cigarette starts burning. PAH is known to cause various carcinomatous conditions in lung, liver and breast.
Chromium causes renal failure, dermatitis and pulmonary cancer. Two kinds of chromium, 'trivalent' and 'hexavalent' are seen in nature. Hexavalent chromium is highly toxic and carcinogenic and is found in cigarette.
Just like PAH, nitrosamines also causes damage to the DNA leading to various kinds of cancers like brochogenic carcinoma.
7. Carbon monoxide
CO is the compound in cigarette smoke which causes Low Birth Weight in newborns of mothers who smoke. CO is highly permeable through the placental barrier and has 2-3 times more affinity for fetal hemoglobin (HbF) than adult hemoglobin (HbA). It displaces oxygen from the binding site on hemoglobin and this causes reduced blood supply to various organs.
Other chemical carcinogens found in cigarette smoke are nickel, lead, cobalt, beryllium, acetaldehyde, hydrazine, benzene, O-Toluidine, Formaldehyde, 1,3-Butadine, Acrolein etc.
Lung cancer due to cigarette smoking
Lung cancer arises from the respiratory epithelium, bronchi, bronchioles and alveoli. Every year primary carcinoma of lung affects 173,000 people in US. 86% of these people with lung cancer die within 5 years of diagnosis.
WHO has classified lung cancer according to the histological types. Following table shows the classification of lung cancer.
Histological type Frequency
Non-small cell carcinoma
Brochoalveolar carcinoma 3%
Squamous cell carcinoma 29%
Large cell carcinoma 9%
Small cell carcinoma 18%
Adenoid cystic carcinoma
Of these various types of lung cancers first four constitute nearly 85% of all cancers. Cigarette smoking causes most commonly Small cell carcinoma of lung.
Signs and Symptoms
Lung cancer causes tumor growth, invasion of lymphatics and distant metastasis through blood. Endobronchial growth of the tumor causes cough, hemoptysis, wheeze and dyspnea and other related clinical symptoms. Pain may be caused by the growth of tumor into pleura and chest wall. Hoarseness of voice may be seen due to the involvement of recurrent laryngeal nerve. Brain and bone metastasis are common with lung cancers and main symptoms include neurological deficits and deep bone pain.
Exposure of lungs to carcinogens and tumor promoters present in cigarette smoke is the most common cause of lung cancer. At molecular level inactivation of tumor suppressor gene (recessive oncogene) and activation of oncogene are the causes of the carcinomas.
5-15% of lung cancer is diagnosed when the patient is asymptomatic and undergoes a routine chest x-ray. Screening tests are done in high risk individuals and these include sputum cytology, chest x-ray and spiral CT.
Hitological diagnosis is done by obtaining tumor tissue by bronchoscopy. CT guided fine needle aspiration can also be used to obtain tissue sample.
Treatment of lung cancer depends on the stage of the disease. TNM staging is used to stage lung cancer (T for tumor size, N for regional node involvement and M for presence or absence of metastasis). Surgical resection of the tumor, radiotherapy and adjuvant chemotherapy or a combination of these is used to treat lung cancer depending upon the type and stage of the carcinoma.
Effects of smoking on society
A report by CDC, (2001) shows that 46 million Americans are smokers, indicating that nearly one in four adults smoke cigarette. Deaths due to smoking exceed the combined death rates of alcohol, car accidents, suicide, AIDS, homicide, and illegal drugs taken together.
Effects on health care cost
Each year US spends nearly 193 billion dollars on tobacco use. Nearly 100 billion dollars is used for the treatment of medical conditions related to smoking and another 100 billion dollars in earning and productivity that are lost due to smoking.
Peer pressure is one of the most common trigger to start smoking in children and adolescents. Children are very easily influenced by the habits of their friends. Adolescents are pressured by their mates to smoke and most of the time they are forced to do so in order to stay in the group and to please their friends. The age at which a person starts his first smoking is largely influenced by the behaviors of his peers.
Parental smoking influences adolescent smoking. There is always a tendency for a child to accept its parents as role models and do what they do. Studies show that when parents stop smoking even the children stop smoking. But, there are many other studies which conclude that there is no association between parental smoking and their children inculcating the same.
Smoking in movies and television
A study done by Sargent J.D. and Dalton M.A, et al, shows that there is association between viewing movie depictions of tobacco use and higher receptivity to smoking tendencies prior to originally trying the behavior, amongst adolescents. Indian government has now banned portrayal of tobacco use in movies.
Prevention of smoking
Public information and education
The best way to prevent smoking is to create public awareness about the hazards of smoking through mass media. The target population should be the entire population with greatest emphasis laid on young people and school children. Nothing less than a national anti-smoking campaign will be needed to change the human behavior or life styles associated with smoking. Prevention of smoking must be an essential part of national health policy (Park).
Legislative and restrictive measures
Almost all countries in the world have their own laws which restrict people from smoking. It is imperative that all the laws are strong and followed by the public.
Age restriction is one of the ways to curb the use of tobacco by minors. In US all the states as well as District of Columbia has laws which restricts the sale of cigarettes to the minors. Minimum age for a person to buy cigarette is 18yeras in all states except Alabama, Alaska, New Jersey and Utah where minors are defined as people below the age of 19 years.
One way to prevent smoking is to increase the price of cigarette by increasing the taxes on it. It mainly produces an attitude change amongst youth smokers who are more cost conscious. "â€¦â€¦â€¦a $1 cigarette tax hike would immediately decrease youth smoking by 30 percent while reducing overall smoking rates by 11 percent".(Chaloupka F. J. Tobacco taxation, Impacteen).
(Chaloupka F. J. Tobacco taxation, Impacteen).
Restriction on cigarette advertising
US-based multinational Philip Morris - the world's biggest cigarette company - was the world's ninth largest advertiser in 1996, spending more than $3 billion (WHO).
Lots of countries have restrictions that really limit or ban tobacco displays. Three countries (Iceland, Ireland and Thailand) already have laws that ban all tobacco displays
Each option has pluses and minuses:
What that means
1. Same laws
Same laws as now but with better education and enforcement.
Wouldn't cost much more than now.
Wouldn't deal with all the problems. People would still see tobacco products all the time.
2. Change and strengthen the laws
Could be things like, health-warning posters or only allowing one tobacco display in each store.
A health-warning poster would make people more aware of the dangers of smoking.
Could reduce the number of displays that people see.
Wouldn't deal with all the problems. People would still see tobacco products all the time.
In 2008, by law, all cigarette packets will need to include a graphic health warning anyway.
3. Ban tobacco displays
Two options: either ban tobacco displays in all places or ban them in all places that people who are under the age of 18 can go.
Young people wouldn't see tobacco products. This would help stop people who have quit smoking from being tempted.
There are very few places that sell tobacco so it wouldn't be much different from a total ban.
People won't know where they can buy cigarettes or what cigarettes are available.
(Published in December 2007 by the Ministry of Health, PO Box 5013, Wellington, New Zealand)
Displaying adverse health effect of cigarette smoking on the cartons is one way of informing the smokers and thus discourages them from the habit. The warnings should be large, both in graphics and in words and should be easy to comprehend so that people who are illiterate should also be well informed. Most warnings do not inform the smoker well about the health consequences.
Smoking bans on public places
Restriction of smoking in public places will not only curb the use of cigarette but will also prevent passive or second hand smoking which is equally dangerous as first hand smoking. In US smoking is prohibited in government buildings. Some sates have laws which prevent smoking in bars and restaurants too. In India it is not allowed to smoke in all public places like bus stations and railway stations. It is also imperative on governments to make laws and also ensure that the laws are followed by all and people who do not follow it be punished.
Smoking cessation activities
Smoking cessation activities are primarily designated to those activities that relieve the smoker of abstinence symptoms like sleeplessness, cravings for smoking, dizziness, constipation etc. The primary line of treatment is use of sedatives and nicotine tablets and laxatives. Major research towards this are being carried out by the WHO under the common collective title "Smoking Cessation Activities".
National and international co-ordination
Political and non-political organizations at local, national and international levels come together towards smoking cessation activities. Notable among them being American Lung Cancer Society, Danish Cancer Association, Swedish International development Agency and Danish international development agency.
Treatment of smoking and dependence
As described, nicotine is the additive agent present in cigarette smoke. Various symptoms of nicotine addiction are craving for tobacco, anxiety, irritability, restlessness, difficulty concentrating, headache, drowsiness, stomach upset, even constipation or diarrhea. Symptomatic treatment is given for some of the above problems like laxatives for constipation.
All patients coming to see a doctor should be asked about their smoking history and should be encouraged to quit smoking if they are chronic smokers. The following table shows the guideline followed by medical practitioners to treat smokers to quit their habit.
Identify smokers willing to quit
Assist the patient in quitting
Pharmacologic intervention-first line
Nicotine oral inhaler
Nicotine nasal inhaler
Pharmacologic intervention-second line
Medical personnel counseling
Smoking cessation program
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