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ABOUT
CANCER
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CANCER INFORMATION |
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What is cancer? |
| Human
body is made of small building blocks called cells.
The cells perform various functions to keep us healthy.
They often multiply for growth and repair of tissues.
Normally cell growth or multiplication is balanced
by cell loss or cell death. Cancer is a group of
diseases characterized by uncontrolled growth and
spread of cells. If the abnormally behaving cells
are not controlled, they can lead to death. |
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What are the types of cancer? |
| Cancer
is not one disease but a group of diseases. Cancers
arising from different organs have different symptoms
and different behaviour. Some of the cancer are
very mild and can be controlled easily by treatment
while some are very aggressive and do not respond
to treatment. There are others which have an intermediate
behavior. Two broad groups of cancers can be considered:
cancers of blood forming system which in common
parlance are also called "blood cancers". These
include leukemias, lymphomas, myelomas, etc.
Cancers of other systems or organs are also commonly
called "solid cancers".
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How does a cancer grow and spread? |
| As
mentioned above, the cells constituting a cancer
have abnormal growth behavior. They keep on multiplying
without control. The excess production of cells
leads to formation of a swelling (also called a
tumor). These cells also have an abnormal tendency
to damage surrounding tissueS through invasion. By invading local tissues, cancer can interfere
with the function of the organs affected. Cancer
cells also tend to spread to other parts of the
body through two systems of circulation in the body.
Through the lymphatic system, the cancer spreads to
lymph nodes draining the cancer bearing organ and
then to other parts of the body. Through the blood
stream such as lung, liver, bones, brain, etc.
These organs are commonly affected by spread of
the cancer through bloodstream. Spread of cancer
to other parts of the body is called metastasis.
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How does cancer develop? |
| The
functioning of all parts of the human body at all
levels is governed and controlled by the genes.
The genes can be thought of as a large and elegant
software or information store which controls the
development of human body and its normal functioning.
The genes are responsible for cell multiplication,
cell growth and cell death. All cancers are caused
by some abnormality in the genes. Abnormality in
the genes or mutations arise because of different
agents which can cause damage to the genes such
as chemicals, radiations, viruses, etc. |
| Many
different types of genes are there in the human
body. There are four main types of genes which can
contribute to occurrence of cancer by being abnormal.
They are oncogenes, tumor suppressor genes, DNA
repair genes, and genes related to "cell death mechanisms".
A lot of research is going on to find out the complete
genetic basis of cancer and this is likely to lead
to new treatment options in future. |
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What are the causes of cancer? |
| As
mentioned above, the basic mechanism of development
of cancer is damage to genes. Any agent which can
lead to gene damage is a potential cause of cancer.
Among the common mechanisms, chemicals are one of
the important causes. These chemicals may be from
Tobacco or chemicals present in food, air, water,
etc. Chemicals which have the potential to cause
cancer are called carcinogens. Besides chemicals,
radiation is another important cause of cancer.
Radiation can arise from cosmic rays (rays from
space), nuclear power plants, other radioactive
sources, x-ray machines, radioactive ores, etc.
Ultraviolet radiation from the sun can also cause
some cancers, especially of skin. |
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CAUSES OF CANCER |
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Tobacco |
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Smoking:
Cigarette, bidi, cigar, hukka, others |
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Smokeless:
zarda, gutka, khaini, snuff, etc. |
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Alcohol
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Infections
(viruses, parasites, bacteria) |
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Electromagnetic
radiation (ionizing radiation, ultraviolet
rays, others) |
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Diet
(dietary carcinogens) |
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Occupational
exposure to carcinogens |
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Pollution
(air/water/food) |
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Reproductive hormones |
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