Cancer is a disease which is
very difficult to cure even you can say incurable disease. Still we can fight
with It. Now a day’s many different kinds of cancer viruses are detected, so
it’s very difficult to fight with all. But it’s not impossible. There are many
reasons behind cancer, so first you should know what cause cancer so that you
will aware of that. We celebrate Feb 4 – world cancer day, as cancer is a kind
of incurable & painful disease. So through this day we aware people how to
take care of them. We can’t kill all cancer virus even we can’t change gene mutation
but we can change our life style, we can stay away from those things what cause cancer.
So please read this article
of cancer awareness, hope it will help you a lot . I am not a doctor but whatever
knowledge I have or I gained from different sources I wanna share with you all.
So please read & take care yourself, stay healthy. Health is a big issue in
everyone’s life. You can compromise with wealth not with health. So be careful.
Even this time I have chosen
a project which is based on cancer cure , i choose this because cancer is a big issue right now. My project is on nano-robot for cancer
curing. As day by day cancer is becoming a general issue, so if we wanna fight
with them we have to take steps wisely. We have to take help of engineering. As
medicinal treatment is very difficult to fight with disease. So its better
fight with them through some other agents like nano robot. As medicine work slowly, so it’s
better to take the help of machine like robot. Which can help us many ways? I am
working on project based on bio-nano robot for cancer detecting & curing , I
don’t know how much I’ll be success here
as it’s a experimental issue , hope if I’ll get a chance to do something more
then I’ll work on it. I wanna help mankind through my knowledge. I m not worry
as I couldn’t get medical, here also I can help people through my bio + engineering
knowledge. I am trying my best. Maybe this time I get less success (in my
project) as it’s a graduation level & I have no much vast idea. I wish, god
help me so that I can help people in future.
WISH & WORK IS IN MY HAND.
I don’t know my future.
CAUSES OF CANCER
Some general things which causes cancer
acetaldehyde, acrylamide, acrylonitril, abortion, agent
orange, alar, alcohol, air pollution, aldrin, alfatoxin, arsenic, arsine,
asbestos, asphalt fumes, atrazine, AZT, baby food, barbequed meat, benzene,
benzidine, benzopyrene, beryllium, beta-carotene, betel nuts, birth control
pills, bottled water, bracken, bread, breasts, brooms, bus stations,
calcium channel blockers, cadmium, candles, captan, carbon black, carbon
tetrachloride, careers for women, casual sex, car fumes, celery, charred
foods, cooked foods, chewing gum, Chinese food, Chinese herbal
supplements, chips, chloramphenicol, chlordane, chlorinated camphene,
chlorinated water, chlorodiphenyl, chloroform, cholesterol, low cholesterol,
chromium, coal tar, coffee, coke ovens, crackers, creosote, cyclamates,
dairy products, deodorants, depleted uranium, depression,
dichloryacetylene, DDT, dieldrin, diesel exhaust, diet soda, dimethyl
sulphate, dinitrotouluene, dioxin, dioxane, epichlorhydrin, ethyle acrilate,
ethylene, ethilene dibromide, ethnic beliefs,ethylene dichloride, Ex-Lax, fat,
fluoridation, flying, formaldehyde, free radicals, french fries, fruit,
gasoline, genes, gingerbread, global warming, gluteraldehyde, granite, grilled
meat, Gulf war, hair dyes, hamburgers, heliobacter pylori, hepatitis B
virus, hexachlorbutadiene, hexachlorethane, high bone mass, hot tea,
HPMA, HRT, hydrazine, hydrogen peroxide, incense, infertility, jewellery,
Kepone, kissing, lack of exercise, laxatives, lead, left handedness, Lindane,
Listerine, low fibre diet, magnetic fields, malonaldehyde, mammograms,
manganese, marijuana, methyl bromide, methylene chloride, menopause,
microwave ovens, milk hormones, mixed spices, mobile phones, MTBE, nickel,
night lighting, night shifts, nitrates, not breast feeding, not having a twin,
nuclear power plants, Nutrasweet, obesity, oestrogen, olestra, olive oil,
orange juice, oxygenated gasoline, oyster sauce, ozone, ozone depletion,
passive smoking, PCBs, peanuts, pesticides, pet birds, plastic IV bags, polio
vaccine, potato crisps (chips), power lines, proteins, Prozac, PVC, radio
masts, radon, railway sleepers, red meat, Roundup, saccharin, salt, sausage,
selenium, semiconductor plants, shellfish, sick buildings, soy sauce,
stress, strontium, styrene, sulphuric acid, sun beds, sunlight, sunscreen,
talc, tetrachloroethylene, testosterone, tight bras, toast, toasters, tobacco,
tooth fillings, toothpaste (with fluoride or bleach), train stations,
trichloroethylene, under-arm shaving, unvented stoves, uranium, UV
radiation, Vatican radio masts, vegetables, vinyl bromide, vinyl
chloride, vinyl fluoride, vinyl toys, vitamins, vitreous fibres,
wallpaper, weedkiller (2-4 D), welding fumes, well water, weight gain, winter,
wood dust, work, x-rays.
What
causes cancer important issues?
There are about 200
different types of cancer. It can start in any type of body tissue. What
affects one body tissue may not affect another. For example, tobacco smoke that
you breathe in may help to cause lung cancer. Overexposing your skin to the sun
could cause a melanoma on your leg. But the sun won't give you lung cancer and
smoking won't give you melanoma.
Apart from infectious
diseases, most illnesses (including cancer) are multifactorial.
The fundamental cause of
cancer is damaged or faulty genes – the
instructions that tell our cells what to
do. Genes are encoded within DNA, so anything that damages DNA can
increase the risk of cancer. But a number of genes in the same cell need to be
damaged before it becomes cancerous.
Most cancers are caused by DNA damage that accumulates over a
person's lifetime. Cancers that are directly caused by specific genetic faults
inherited from a parent are rare. But we all have subtle variations in our
genes that may increase or decrease our risk of cancer by a small amount.
So cancer risk isn't "all in the
genes", and it's not all down to lifestyle - it's a combination of the
two. We can't change our genetic makeup, but we can all take steps to reduce
our risk of cancer. There are many factors involved. In other words, there is
no single cause for any one type of cancer.
Cancer causing
substances (carcinogens)
A carcinogen is something
that can help to cause cancer. Tobacco smoke is a powerful carcinogen. But not
everyone who smokes gets lung cancer. So there must be other factors at
work as well.
Age
Most types of cancer
become more common as we get older. This is because the changes that make a cell
become cancerous in the first place take a long time to develop. There have to
be a number of changes to the genes within a cell before it turns
into a cancer cell. These changes can happen by accident when the cell is
dividing. Or they can happen because the cell has been damaged by carcinogens
and the damage is then passed on to future cells when that cell divides. The
longer we live, the more time there is for genetic mistakes to happen
in our cells.
Genetic make up
There need to be a number
of genetic mutations within a cell before it becomes cancerous.
Sometimes a person is born with one of these mutations already. This doesn't
mean they will definitely get cancer. But with one mutation from the start, it
makes it more likely statistically that they will develop cancer during their
lifetime. Doctors call this genetic predisposition.
The BRCA1 and BRCA2 breast
cancer genes are examples of genetic predisposition. Women who carry one of
these faulty genes have a higher chance of developing breast cancer than women
who do not.
The BRCA genes are good
examples for another reason. Most women with breast cancer do not have a
mutated BRCA1 or BRCA 2 gene. Less than 3% of all breast cancers are due to
these genes. So although women with one of these genes are individually more
likely to get breast cancer, most breast cancer is not caused by a high risk
inherited gene fault.
This is true of other
common cancers where some people have a genetic predisposition – for example,
colon (large bowel) cancer.
Researchers are looking at
the genes of people with cancer in a study called SEARCH. They also hope
to find out more about how other factors might interact with genes to increase
the risk of cancer.
The immune system
People who have problems
with their immune systems are more likely to get some types of cancer. This
group includes people who
· Have had organ transplants and take
drugs to suppress their immune systems to stop organ rejection
· Have HIV or AIDS
· Are born with rare medical syndromes
which affect their immunity
The types of cancers that
affect these groups of people fall into two, overlapping groups
· Cancers that are caused by viruses,
such as cervical cancer and other cancers of the genital or anal area, some
lymphomas, liver cancer and stomach cancer
· Lymphomas
Chronic infections or
transplanted organs can continually stimulate cells to divide. This continual
cell division means that immune cells are more likely to develop genetic faults
and develop into lymphomas.
Smoking, bodyweight, diet and physical
activity
Many cancer cases are
linked to lifestyle factors such as smoking, alcohol, diet, or being
overweight. In the western world, many of us eat too much red and processed
meat and not enough fresh fruit and vegetables. This type of diet is known to
increase the risk of cancer. Drinking alcohol can also increase the risk of
developing some types of cancer. There is more information about this on the
page about diet causing cancer.
Sometimes foods or food
additives are blamed for directly causing cancer and described as carcinogenic.
This is often not really true. Sometimes a food is found to contain a substance
that can cause cancer but in such small amounts that we could never eat enough
of it to do any harm. And some additives may actually protect us. There
is more about food additives in the page about diet causing
cancer.
Day to day environment
By environmental causes we
mean what is around you each day that may help to cause cancer. This could
include
· Tobacco smoke
· The sun
· Natural and man made radiation
· Work place hazards
· Asbestos
Some of these are avoidable and
some aren't. Most are only contributing factors to causing cancers – part of
the jigsaw puzzle that scientists are still trying to put together. There is
more about this in the page about causes of cancer in the environment.
Cancer cell
Cancer Cell Properties
Cancer cells have characteristics that
differ from normal cells. They all acquire the ability to grow uncontrollably.
This can result from having control of their own growth signals, losing
sensitivity to anti-growth signals, and losing the ability to undergo apoptosis or programmed cell death. Cancer cells
don't experience biological aging and maintain their ability to undergocell
division and growth.
Cancer Viruses
Researchers have long attempted to elucidate
the role that viruses play in causing cancer. Worldwide,
cancer viruses are estimated to cause 15 to 20 percent of all cancers in
humans. Most viral infections however, do not lead to tumor formation as
several factors influence the progression from viral infection to cancer
development. Some of these factors include the host's genetic makeup, mutation
occurrence, exposure to cancer causing agents, and immune impairment. Viruses
typically initiate cancer development by suppressing the host's immune system, causing inflammation
over a long period of time, or by altering host genes.
These cancers and viruses are linked
· Cervical cancer, and other cancers of
the genital and anal area, and the human papilloma virus (HPV)
· Primary liver cancer and the
Hepatitis B and C viruses
· Lymphomas and
the Epstein-Barr Virus
· T cell leukemia in adults and the
Human T cell leukaemia virus
· HPV also probably leads to or
pharyngeal cancer and non melanoma skin cancers in some people
There will be people with
primary liver cancer and with T cell leukaemia who haven't had the related
virus. But infection increases their risk of getting that particular cancer.
With cervical cancer, scientists now believe that everyone with an invasive
cervical cancer has had an HPV infection beforehand.
Many people can be
infected with a cancer causing virus, and never get cancer. The virus only
causes cancer in certain situations. Many women get a high risk HPV
infection, but never develop cervical cancer.
Another example is
Epstein-Barr virus (EBV). These are some facts about EBV
· It is very common – most people are
infected with EBV
· People who catch it late in life get
glandular fever and have an increased risk of lymphoma
· In sub Saharan Africa, EBV infection
and repeated attacks of malaria together cause a cancer called Burkitt's
lymphoma in children
· In China, EBV infection (together with
other unknown factors) causes nasopharyngeal cancer
· In people with AIDs and transplant
patients EBV can cause lymphoma
· About 4 out of 10 cases of Hodgkin's
lymphoma and a quarter of cases of Burkitt's lymphoma (a rare type of non
Hodgkin's lymphoma) seem to be related to EBV infection
Human tumor viruses
Although it is convenient to consider human tumor viruses as a discrete
group of viruses, these six viruses, in fact, have very different genomes, life
cycles, and represent a number of virus families. The path from viral infection
to tumorgenesis is slow and inefficient; only a minority of infected
individuals progress to cancer, usually years or even decades after primary
infection. Virus infection also is generally not sufficient for cancer, and
additional events and host factors, such as immunosuppression, somatic
mutations, genetic predisposition, and exposure to carcinogens must also play a
role.
Hepatitis B and C viruses
Hepatitis C virus is an enveloped RNA virus of the flavivirus family. It
is capable of causing both acute and chronic hepatitis in humans by infecting
liver cells. It is estimated that approximately 3 percent of the world’s population
are hepatitis C carriers . Chronic infection with hepatitis C virus results in
cirrhosis, which in turn can lead to primary hepatocellular carcinoma. Between
1 and 2 percent of infected patients with subsequent compensated cirrhosis will
develop primary hepatocellular carcinoma per year . Transmission of the virus
occurs through the blood, with shared needles in intravenous drug abuse, sexual
activity, and parturition being the primary routes.
The hepatitis B
virus of the family hepadnaviridae is, by contrast, a DNA virus, but the
features of its resulting disease share many similarities with hepatitis C
virus. Hepatitis B virus also is a blood-borne pathogen that can result in
acute and chronic hepatitis. Chronic hepatitis, that is, infections lasting
more than three months, can lead to cirrhosis and liver failure. Chronic
infection also can lead to the development of hepatocellular carcinoma .
Hepatitis B infections is a significant global health problem with an estimated
2 billion people infected and 1.2 million deaths per year attributed to
subsequent hepatitis, cirrhosis and hepatocellular carcinoma .
Epstein-Barr virus (EBV) and human herpesvirus
8 (HHV-8)
EBV and HHV-8 (also known as Kaposi sarcoma herpesvirus) are both
herpesviruses that possess large double-stranded DNA genomes. As with all
herpesviruses, they encode enzymes involved in DNA replication and repair and
nucleotide biosynthesis. They also both possess the ability to establish
latency in B lymphocytes and reactivate into the lytic cycle. Both also are
associated with naturally occurring tumors in humans.
EBV is a ubiquitous
virus that is most commonly known for being the primary agent for infectious
mononucleosis. Up to 95 percent of all adults are estimated to be seropositive,
and most EBV infections are subclinical. EBV also is associated with a number
of malignancies: B and T cell lymphomas, Hodgkin’s disease, post-transplant
lymphoproliferative disease, leiomyosarcomas, and nasopharyngeal carcinomas. Of
these cancers, Burkitt’s lymphoma, post-transplant lymphoproliferative disease,
and leiomyosarcomas show an increased frequency in patients with
immunodeficiency, suggesting a role for immunosurveillance in the suppression
of malignant transformation.
Human Papillomavirus (HPV)
HPV are small non-enveloped DNA tumor viruses that commonly cause benign
papillomas or warts in humans. Persistent infection with high-risk subtypes of
human papillomavirus (HPV) is associated with the development of cervical
cancer. HPV infects epithelial cells, and, after integration in host DNA, the
production of oncoproteins, mainly E6 and E7, disrupts natural tumor suppressor
pathways and is required for proliferation of cervical carcinoma cells . HPV
also is believed to play a role in other human cancers, such as head and neck
tumors, skin cancers in immunosuppressed patients, and other anogenital cancers.
Cervical cancer is
the second leading cause of cancer mortality in women worldwide, causing
240,000 deaths annually . Of approximately 490,000 cases reported each year,
more than 80 percent occur in the developing world, where effective but costly
Pap smear screening programs are not in place . Early precancerous changes and
early cancers detected by Pap smears are effectively treated and cured with
surgical therapy or ablation. In the absence of effective screening, the
disease is detected late. Traditional therapeutic options for cervical cancer
that have advanced beyond definitive surgical treatment are chemotherapy and
radiation therapy, which are associated with many toxicities and do not offer a
lasting cure.
Human T lymphotropic virus type I (HTLV-1)
HTLV-1 is a slow transforming, single stranded RNA retrovirus and is
associated with adult T-cell leukemia . It possesses a diploid genome similar
to other retroviruses: two long terminal repeats flanking gag, pol, and env
genes as well as a number of accessory genes. HTLV-1 has a worldwide
distribution, with an estimated 12 to 25 million people infected. However,
disease is only observed in less than 5 percent of infected individuals. It is
transmitted through blood transfusions, sexual contact, and during parturition.
HTLV-1 displays a special tropism for CD4 cells, which clonally proliferate in
adult T cell leukemia, though how this is effected is not known.
HTLV-1 infection has a very long latency period of 20 to 30 years, but
once tumor formation begins, progression is rapid. Standard chemotherapy often
can bring about an initial response with a partial or complete remission;
however, relapse is common, and median survival is eight months. The HTLV-1Tax gene has been postulated to play an important role in
tumorgenesis through the activation of
viral transcription and the hijacking of cellular growth and cell division
machinery, but the mechanisms leading to adult T cell leukemia are not well
understood. It has been suspected that HTLV-1 infection may not be sufficient
to transform, and recent evidence suggests that the decreased diversity,
frequency, and function of HTLV-1 specific CD8 T cells in the host may play an
important part in the development of adult T-cell leukemia . Therefore,
targeted therapies using peptide, recombinant protein, DNA, and viral vectors
with the goal of generating neutralizing antibody against HTLV-1 and
multivalent cytotoxic T cell response against Tax are under investigation .
Cancer Viruses: Transformation
Transformation
occurs when a virus infects and genetically alters a cell. The infected cell is regulated by the viral genes and has the
ability to undergo abnormal new growth. Scientists have been able to discern
some commonality among viruses that cause tumors. The tumor viruses change
cells by integrating their genetic material with the host cell's DNA. Unlike the integration seen in prophases, this is a permanent
insertion in that the genetic material is never removed. The insertion
mechanism can differ depending on whether the nucleic
acid in the virus is DNA or RNA.
In DNA viruses, the genetic material can be directly inserted into the host's
DNA. RNA viruses must first transcribe RNA to DNA and then insert the genetic
material into the host cell's DNA.
Cancer Viruses: Classes
There are two classes of cancer viruses: DNA and RNA
viruses. Several viruses have been linked to certain types of cancer in humans.
These viruses have varying ways of reproduction and represent several different
virus families.
DNA Viruses
· The Epstein-Barr virus has been linked
to Burkitt's lymphoma. This virus infects B cells of the immune system and epithelial cells.
· The hepatitis B virus has been linked
to liver cancer in people with chronic infections.
· Human papilloma viruses have been
linked to cervical cancer. They also cause warts and benign papillomas.
· Human herpes virus-8 has been linked
to the development of Kaposi sarcoma. Kaposi sarcoma causes patches of abnormal
tissue to develop in various area of the body including under the skin, in the lining of the mouth,
nose, and throat or in other organs.
RNA Viruses
· Human T lymphotrophic virus type 1
(HTLV-I), a retrovirus, has been linked to T-cell leukemia.
· The hepatitis C virus has been linked
to liver cancer in people with chronic infections.
Bacterial infection
Bacterial infections have
not been thought of as cancer causing agents in the past. But studies have
shown that people who have helicobacter pylori (H pylori) infection of their
stomach develop inflammation of the stomach lining, which increases the risk of
stomach cancer. Helicobacter pylori infection can be treated with a combination
of antibiotics.
Research is also looking
at whether substances produced by particular types of bacteria in the digestive
system can increase the risk of bowel cancer or stomach lymphomas. Some
researchers think that particular bacteria may produce cancer causing
substances in some people. But research into this issue is at an early stage.
If bacteria do play a part
in causing cancer this could be important in cancer prevention. Bacterial
infections can often be cured with antibiotics, so getting rid of the infection
could be a way to reduce the risk of these types of cancer.
Bacteria
|
Associated with
|
Salmonella typhi
|
is associated with gallbladder
cancer.
|
Streptococcus bovis
|
is associated with colorectal cancer.
|
Chlamydia pneumonia
|
is associated with lung cancer.
|
Mycoplasma
|
may also have a role in the formation of
different types of cancer.
|
Helicobacter pylori
|
has been linked with certainty to stomach
cancer and may be related to MALT lymphoma, but may also protect certain
individuals from esophageal cancer.
|
PS -Got these information from different sites & books
Cancer slogan – Fight until they get tired to
kill you. (MINE)
