Download - Causal association of Smoking in NCDs
UNIVERSITY OF MAURITIUS
Bachelor of Pharmacy – Year 2
BIOLOGY OF DISEASE 1
TITLE:
Discuss the causal association between cigarette smoking and Non- Communicable Diseases.
Presented by:
NARAINO MAJIE Nabiilah - 1216824
Date of Submission: 24th September 2013
Table of Contents
1. Introduction
2. How Cigarette smoking induces cardiovascular diseases?
3. How Cigarette smoking induces cancer?
4. How Cigarette smoking contributes in chronic lung disease?
5. How Cigarette smoking is involved in Diabetes?
6. Conclusion
7. References
References
1. Hyeon Chang Kim and Sun Min Oh, 2013, Noncommunicable Diseases: Current
Status of Major Modifiable Risk Factors in Korea, J Prev Med Public Health. Vol:
46(4): 165–172.
Available online: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3740221/
Accessed on: 20th Sept 2013
2. Kimberly C. Bowman, Gilbert L. Ross, M.D., Karen L. Schneider & Elizabeth
M. Whelan, Sc.D., M.P.H., 2005, Cigarettes: What the Warning Label Doesn’t Tell
You.
Available online: http://wwwstatic.kern.org/gems/schcom/CigarettesWarningLabelbook.pdf
Accessed on: 20th Sept 2013
3. Scottish Intercollegiate Guidelines Network (SIGN), 2006, Diagnosis and
management of peripheral arterial disease. A national clinical guideline. Edinburgh
(Scotland): Scottish Intercollegiate Guidelines Network (SIGN); (SIGN publication;
no. 89).
Available online: http://www.guideline.gov/content.aspx?id=9924
Accessed on: 20th Sept 2013
4. Anon, 2013, Smoking and cancer, Cancer Research UK
Available online:
http://www.cancerresearchuk.org/cancer-info/healthyliving/smokingandtobacco/smoking-
and-cancer
Accessed on: 22nd Sept 2013
5. Rajshri ., 2008, Mechanism Behind How Tobacco Carcinogens Cause Lung Cancer,
Cancer News
Available online: http://www.medindia.net/news/Mechanism-Behind-How-Tobacco-
Carcinogens-Cause-Lung-Cancer-37348-1.htm
Accessed on: 22nd Sept 2013
6. Penning., 2008, Mechanism Behind How Tobacco Carcinogens Cause Lung Cancer,
Proceedings of the National Academy of Sciences
Available online: Mechanism Behind How Tobacco Carcinogens Cause Lung Cancer
| Medindia http://www.medindia.net/news/Mechanism-Behind-How-Tobacco-
Carcinogens-Cause-Lung-Cancer-37348-1.htm#ixzz2fdD8huwL
Accessed on: 22nd Sept 2013
7. Sir Richard Doll, 2001, Lung cancer and tobacco consumption, International
Journal of Epidemiology, Volume 30 , Issue 1, Pp. 30-31.
Available online: http://ije.oxfordjournals.org/content/30/1/30.full
Accessed on: 22nd Sept 2013
8. D. P. Lane, 1992, p53, guardian of the genome, Nature 358, 15 – 16
Available online:
http://www.nature.com/nature/journal/v358/n6381/pdf/358015a0.pdf
Accessed on: 22nd Sept 2013
9. Anon, 2006, Smoking & lung disease, Quit [Information sheet]
Available online:
http://www.oxygen.org.au/downloads/sadownloads/infosheet_lung_disease.pdf
Accessed on: 22nd Sept 2013
10. Alice Park, 2011, Why Smoking Is Especially Bad If You Have Diabetes?, Health &
Family; TIME (Online Medical Newspaper).
Available online: http://healthland.time.com/2011/03/27/why-smoking-is-a-bad-idea-
for-diabetics/
Accessed on: 22nd Sept 2013
Introduction
A non-communicable disease (NCD) is a medical condition or disease that is by definition
non-infectious and non-transmissible among people. Currently, NCDs are the leading causes
of death and disease burden worldwide. The four main types of NCDs, including
cardiovascular disease, cancer, chronic lung disease, and diabetes, result in more than 30
million deaths annually. To reduce the burden of NCDs on global health, current public
health actions stress the importance of preventing, detecting, and correcting modifiable risk
factors; controlling major modifiable risk factors has been shown to effectively reduce NCD
mortality. The World Health Organization's World Health Report 2002 identified tobacco
use, alcohol consumption, overweight, physical inactivity, high blood pressure, and high
cholesterol as the most important risk factors for NCDs. Accordingly, the present report set
out to review the prevalence and trends of these modifiable risk factors in the Korean
population. Over the past few decades, we observed significant risk factor modifications of
improved blood pressure control and decreased smoking rate. However, hypertension and
cigarette smoking remained the most contributable factors of NCDs. Moreover, other major
modifiable risk factors show no improvement or even worsened. The current status and trends
in major modifiable risk factors reinforce the importance of prevention, detection, and
treatment of risk factors in reducing the burden of NCDs on individuals and society. (Hyeon
Chang Kim and Sun Min Oh, 2013)
Dr. Margaret Chan, Director-General of the World Health Organization explained that:
"The rise of chronic non-communicable diseases presents public health with an enormous
challenge. For some countries, it is no exaggeration to describe the situation as an
impending disaster. I mean a disaster for health, for society, and most of all for national
economies ..... Implement the WHO Framework Convention on Tobacco Control ... There is
no other 'best buy' for the money on offer."
We can clearly understand that Tobacco use is the only risk factor shared by all four main
categories of NCDs. Tobacco accounts for nearly one in six deaths from NCDs and kills
nearly six million people worldwide each year.
One of the astonishing things about tobacco is the number and variety of fatal and disabling
diseases and conditions it causes.
Tobacco causes at least 16 different types of cancer. It is most closely associated with
lung cancer, the world’s leading cause of cancer deaths, accounting for nearly one in
five cancer deaths. Tobacco use is known to cause several cancers of the throat and
oral cavity, as well as cancer in diverse sites, such as the bladder, kidney, stomach and
uterine cervix. Smokeless tobacco causes oral and other cancers, hypertension and
heart disease.
Cardiovascular disease is the leading cause of death in the world. Smoking increases
the risk of heart disease and stroke by two to four times.
Smoking causes chronic lung diseases that can be severely disabling or fatal,
increasing the risk of death 12 times.
Smoking is an independent risk factor for diabetes, and it has been estimated that 12%
of diabetes incidence in the United States is attributable to smoking. Diabetics who
smoke have an increased risk of death, and of complications associated with diabetes,
such as amputations and problems with vision.
How Cigarette smoking induces cardiovascular diseases?
Cardiovascular disease (CVD) incorporates the disorders of the heart and circulatory system,
including coronary heart disease (angina and heart attacks), peripheral arterial disease,
aneurysms and stroke.
Smoking is a leading cause of cardiovascular disease, causing around 25,000 deaths a year
from heart and circulatory disease. Around one in five premature deaths from heart and
circulatory disease are linked to smoking.
Inhaling tobacco smoke causes several immediate responses within the heart and its blood
vessels.
Within one minute of starting to smoke, the heart rate begins to rise: it may increase by as
much as 30 percent during the first 10 minutes of smoking. Nicotine stimulates the body to
produce adrenaline which makes the heart beat faster and raises blood pressure, therefore
causing the heart to work harder. The carbon monoxide in tobacco smoke exerts a negative
effect on the heart by reducing the blood’s ability to carry oxygen. Smoking can increase
blood cholesterol levels. Furthermore, the ratio of high-density lipoprotein cholesterol; the
“good” cholesterol, to low-density lipoprotein cholesterol; the “bad” cholesterol, tends to be
lower in smokers compared to non-smokers. Smoking also raises the levels of fibrinogen; a
protein which causes blood to clot, and increases platelet aggregation which makes the blood
stickier. Carbon monoxide attaches itself to haemoglobin which is the oxygen-carrying
pigment in red blood cells much more easily than oxygen does, which reduces the amount of
oxygen available to the tissues. All these factors make smokers more at risk of developing
various forms of atherosclerotic disease, which is when coronary arteries become narrowed
by a gradual build up of fatty material within their walls. As the atherosclerotic process
progresses, blood flows less easily through rigid and narrowed arteries and the blood is more
likely to form a thrombosis (clot). This sudden blockage of an artery may lead to a fatal heart
attack, a stroke or gangrene of the leg. (Kimberly C. Bowman et al., 2005)
Coronary Heart Disease (CHD)
The heart needs a steady supply of oxygen-rich blood to function effectively. Coronary heart
disease (also known as coronary artery disease or ischemic heart disease) is a general term
that describes conditions caused by an interrupted or diminished blood flow through the
coronary arteries to the heart muscle. The most common way that this flow of oxygen-rich
blood becomes reduced is by the build up of fatty deposits (atherosclerosis) or the formation
of a blood clot (thrombosis) in the arteries.
When the blood supply to the heart is interrupted, it sometimes causes the chest pain known
as angina. When the blood supply is cut off completely, a myocardial infarction or heart
attack occurs, which may cause permanent damage to the heart muscle.
Peripheral Arterial Disease (PAD)
Peripheral Arterial Disease (also called Peripheral Vascular Disease) is a disease that affects
the arteries. Most forms of PAD are caused by a gradual build-up of fatty material in the
walls of the artery, a condition called “atherosclerosis”. Over time, one or more of the
principal arteries may become so narrow that they are unable to deliver oxygen-rich blood to
the limbs. In severe cases, the blockage can cause gangrene requiring amputation. (SIGN,
2006)
Aneurysm
An aneurysm is a bulge in a blood vessel that is caused by a weakness in the vessel wall. As
the blood passes through the weakened part of the vessel, the blood pressure causes it to
bulge outwards like a balloon. There is a danger that the aneurysm will cause the artery to
burst (rupture) causing organ damage or internal bleeding, both of which can be fatal.
Aneurysms occur most commonly in the aorta (the main artery in the heart that pumps blood
out into the body) or in the brain (referred to as an intracranial aneurysm) but can occur in
any artery in the body.
Stroke
A stroke (also known as cerebral thrombosis or cerebro-vascular disease) occurs when blood
flow to the brain is interrupted causing brain cells to become damaged or die.
It can affect the way your body or mind functions. It is currently the second most common
cause of death world-wide after heart disease. The World Health Organization has predicted
that this will still be the case in 2030, with stroke expected to account for 12.1% of all deaths.
Smokers are more likely to have a stroke than non-smokers and the risk increases with the
number of cigarettes smoked.
How Cigarette smoking induces cancer?
Smoking causes more than four in five cases of lung cancer. Lung cancer has one of the
lowest survival rates of all cancers, and is the most common cause of cancer death
worldwide. The good news is that most of these deaths are preventable, by giving up smoking
in time. (Cancer Research UK, 2013)
Smoking also increases the risk of over a dozen other cancers including cancers of the mouth,
larynx (voice box), pharynx (upper throat), nose and sinuses, oesophagus (food pipe), liver,
pancreas, stomach, kidney, bladder, cervix and bowel, as well as one type of ovarian cancer
and some types of leukaemia. There is also some evidence that smoking could increase the
risk of breast cancer.
Tobacco smoke contains more than 70 different cancer-causing substances. When you inhale
smoke, these chemicals enter your lungs and spread around the rest of your body.
Scientists have shown that these chemicals can damage DNA and change important genes.
This causes cancer by making your cells grow and multiply out of control. There are two
types of cancer-causing agents in cigarettes; a nicotine-derived chemical and polycyclic
aromatic hydrocarbons (PAHs).
Earlier studies have shown how PAHs damage DNA, with the emphasis on how PAHs bind
directly to DNA itself, leading to the mutations in critical genes that cause disease. (Rajshri,
2008)
Now, researchers have shown that PAHs, via oxidative stress, can also lead to mutations in
critical genes important in lung cancer.
Oxidative stress is the accumulation of destructive molecules called free radicals that can lead
to cell death. Free radicals damage cell membranes, proteins, or genetic material by
'oxidizing' them, the same way oxygen causes iron to rust. It was shown from studies that
enzymes called AKRs are responsible for the oxidative stress from PAHs in the human lung
cells. The AKR enzymes transform PAHs to produce oxygen free radicals. These oxygen
radicals bind to DNA, and if this damage is not repaired it leads to mutations that are carried
through to the next generation of cells. (Penning., 2008)
How Cigarette smoking contributes in chronic lung disease?
Many smokers can tell that smoking is causing damage to their lungs. They sometimes feel
short of breath and puff more easily than they used to.
These things happen because every time a cigarette is smoked, the following occurs:
The minute hairs in the upper airways (cilia) are paralysed or damaged by the
chemicals in cigarette smoke.
The lungs are irritated so the airways narrow, which encourages phlegm and makes it
harder to breathe.
Carbon monoxide, a poison, is forced into the blood and restricts the oxygen carrying
capacity of the blood.
Smoking has been linked to a number of respiratory diseases:
Chronic Obstructive Pulmonary Disease (COPD) - a group of diseases including
chronic bronchitis and emphysema
Lung cancer and other cancers of the airways, including the oesophagus and larynx
Asthma.
Chronic Obstructive Pulmonary Disease (COPD)
Chronic obstructive pulmonary disease (COPD) is a long-term lung disease that causes
shortness of breath, which initially occurs with exertion and becomes progressively worse
over time.
Limitation of the airways due to COPD is irreversible.
Initially, shortness of breath may happen only when walking up hills or stairs. But with
serious disease, even walking and normal activities will become difficult. People with these
diseases often live for many years in varying degrees of discomfort and disability.
The following three things occur due to cigarette smoking:
• Inflammation of the bronchi, causing excessive amounts of mucus to be produced.
This leads to coughing and phlegm production, and breathlessness. It may be associated with
low-grade infection in the airways; this disease is named chronic bronchitis.
• The alveoli (air sacs) are gradually destroyed, so it becomes difficult to get enough oxygen;
this disease is called Emphysema.
• Bronchi become narrow and floppy, making it difficult to breathe out.
Lung cancer
The other major respiratory disease that smoking causes is lung cancer - the first major
disease to be causally linked with smoking.
New evidence has identified an important gene - p53, found in the nucleus of every cell. P53
is described as the 'guardian of the genome' and one of its main roles is to clean up any errors
or changes that occur within copied cells. This means that any cell with damaged p53 is
highly susceptible to cancer. In 1996, scientists made a direct link between
Smoking and lung cancer when they proved that benzopyrene, a carcinogen found in high
concentrations in cigarette smoke, directly damages p53, and leaves a distinctive signature.
(D. P. Lane, 1992)
The risk of developing lung cancer is related to both how long and how much a person has
smoked. For instance, a person who takes up smoking in their teens is five times more likely
to die of lung cancer than someone who starts after their mid twenties. Smokers' risk of dying
from lung cancer is more than 10 times that of a non-smoker, and heavy smokers are between
15 and 25 times more at risk. (Quit [Information sheet], 2006)
Asthma
Asthma is a very common condition affecting the airways in the lungs. These become
inflamed and irritable. When these irritable airways are exposed to certain 'triggers' the
airways narrow, leading to difficulty in breathing.
The result is a reduction of the flow of air in and out of the lungs. The most common
symptoms of asthma are difficulty in breathing or shortness of breath, a feeling of tightness in
the chest, wheezing and coughing (particularly at night). Asthma attacks can occur without
warning, but are often related to poor control.
Tobacco smoke is a powerful trigger for people with asthma, and one that all children should
avoid. Smoking should be avoided anywhere around infants and children - like family rooms,
kitchens, cars etc. Young people and adults with asthma should not smoke, as these further
damages lungs. Where possible, they should try and avoid places where other people smoke
too. Exposure to cigarette smoke during pregnancy and early childhood significantly
increases the risk of children developing asthma, and has also been shown to make asthma
attacks more severe. (Quit [Information sheet], 2006)
Other cancers of the respiratory system
Smoking is a major cause of cancers of the oral cavity, oesophagus and larynx. The use of
alcohol in combination with smoking greatly increases smokers' risk for these cancers.
How Cigarette smoking is involved in Diabetes?
Cigarettes contain more than 4000 chemical compounds and at least 400 toxic substances.
Everyone risks damaging their health through smoking a cigarette, pipe or cigar, but for
people with diabetes the risk may be even greater. Cigarette smoking increases the risk for
type 2 diabetes incidence. Nicotine, acknowledged as the major pharmacologically active
chemical in tobacco, is responsible for the association between cigarette smoking and
development of diabetes. Someone having diabetes has an increased chance of developing
cardiovascular disease, such as a heart attack, stroke or circulatory problems in the legs.
Combine this with smoking (which can also double the risk of complications); the chances of
developing these diseases even higher.
Researchers have long known that diabetes patients who smoke have higher blood sugar
levels, making their disease more difficult to control and putting them at greater danger of
developing complications such as blindness, nerve damage, kidney failure and heart
problems. (Alice Park, 2011)
It was reported by Xiao-Chuan Liu, a professor of chemistry at the California State
Polytechnic University that nicotine, when added to human blood samples, raised the levels
of haemoglobin A1c (HbA1c) by as much as 34% and a similar result was expected for
diabetic people. (Alice Park, 2011)
Haemoglobin A1c is a combination of haemoglobin and glucose which is a standard indicator
of blood sugar content in the body.
According to a research performed by Prof. Liu, it was confirmed that nicotine is responsible
for developing diabetes in a smoker who is non-diabetic. The higher A1c levels rise in the
blood, he says, the more likely it is that other protein complexes, which build up in various
tissues of the body, from the eyes, heart and blood vessels, can form, leading to blockages in
circulation and other complications. But perhaps more importantly, the results also suggest
that nicotine replacement products such as patches and nicotine-containing electronic
cigarettes are not a safe option for diabetes patients either. Because they still contain nicotine,
these products are just as likely to boost A1c levels as cigarettes are.
It is also observed that patients with type 2 diabetes mellitus (DM2) are at risk for micro and
macro vascular complications, which could be observed in heavy smokers.
Conclusion
We all know that cigarette smoking is injurious to health and with all these details on
different diseases linked to smoking, it implies that smoking is even more dangerous as it
seems to be. We have seen how smoking is correlated to NCDs including cardiovascular
diseases, cancer, lung diseases and eventually diabetes and through statistics, smoking is
estimated to cause about 71% of all lung cancer deaths, 42% of chronic respiratory disease
and nearly 10% of cardiovascular disease worldwide. (WHO Publication, 2011)
As health science representatives, it is our duty to make the public aware of the risk factors
associated with smoking. The best way to avoid or minimize such diseases is to quit smoking.
The good points in quitting smoking is a healthier life style, reduced risk of developing
diseases mentioned above, prolonged life and save money.