Cancer is the general name for a group of more than 100 diseases in which
cells in a part of the body begin to grow out of control. Although there are
many kinds of cancer, they all start because abnormal cells grow out of
control. Untreated cancers can cause serious illness and even death.
Normal Cells in the
Body
The body is made up of trillions of living cells. Normal body cells grow,
divide, and die in an orderly fashion. During the early years of a person's
life, normal cells divide faster to allow the person to grow. After the person
becomes an adult, most cells divide only to replace worn-out or dying cells or
to repair injuries.
How Cancer Starts?
Cancer begins when cells in a part of the body start to grow out of
control. There are many kinds of cancer, but they all start because of out-of-control
growth of abnormal cells.
Cancer cell growth is different from normal cell growth. Instead of
dying, cancer cells continue to grow and form new, abnormal cells. Cancer cells
can also invade (grow into) other tissues, something that normal cells cannot
do. Growing out of control and invading other tissues are what makes a cell a
cancer cell.
Cells become cancer cells because of damage to DNA. DNA is in every cell
and directs all its actions. In a normal cell, when DNA gets damaged the cell
either repairs the damage or the cell dies. In cancer cells, the damaged DNA is
not repaired, but the cell doesn't die like it should. Instead, this cell goes
on making new cells that the body does not need. These new cells will all have
the same damaged DNA as the first cell does.
People can inherit damaged DNA, but most DNA damage is caused by mistakes
that happen while the normal cell is reproducing or by something in our
environment. Sometimes the cause of the DNA damage is something obvious, like
cigarette smoking. But often no clear cause is found.
Cancer harms the body when damaged cells divide uncontrollably to form
lumps or masses of tissue called tumors (except in the case of leukemia where
cancer prohibits normal blood function by abnormal cell division in the blood
stream). Tumors can grow and interfere with the digestive, nervous, and
circulatory systems, and they can release hormones that alter body function.
Tumors that stay in one spot and demonstrate limited growth are generally
considered to be benign.
More dangerous, or malignant, tumors form when two things occur:
- A cancerous cell
manages to move throughout the body using the blood or lymph systems,
destroying healthy tissue in a process called invasion
- That cell manages to divide and grow, making new blood vessels to feed itself in a process called angiogenesis.
How Cancer Spreads?
Cancer cells often travel to other parts of the body, where they begin to
grow and form new tumors that replace normal tissue. This process is called
metastasis. It happens when the cancer cells get into the bloodstream or lymph
vessels of our body. No matter where a
cancer may spread, it is always named for the place where it started.
For example, breast cancer that has spread to the liver is still called
breast cancer, not liver cancer. Likewise, prostate cancer that has spread to the
bone is metastatic prostate cancer, not bone cancer.
Different types of cancer can behave very differently. For example, lung
cancer and breast cancer are very different diseases. They grow at different
rates and respond to different treatments. That is why people with cancer need
treatment that is aimed at their particular kind of cancer.
Not all tumors are cancerous. Tumors that aren't cancer are called
benign. Benign tumors can cause problems – they can grow very large and press on
healthy organs and tissues. But they cannot grow into (invade) other tissues.
Because they can't invade, they also can't spread to other parts of the body
(metastasize). These tumors are almost never life threatening.
Cancers Classification
There are five broad groups that are used to classify cancer.
- Carcinomas are
characterized by cells that cover internal and external parts of the body
such as lung, breast, and colon cancer.
- Sarcomas are
characterized by cells that are located in bone, cartilage, fat,
connective tissue, muscle, and other supportive tissues.
- Lymphomas are
cancers that begin in the lymph nodes and immune system tissues.
- Leukemias are
cancers that begin in the bone marrow and often accumulate in the
bloodstream.
- Adenomas are cancers that arise in the thyroid, the pituitary gland, the adrenal gland, and other glandular tissues.
Cancers are often referred to by terms that contain a prefix related to
the cell type in which the cancer originated and a suffix such as -sarcoma,
-carcinoma, or just -oma. Common prefixes include:
- Adeno- = gland
- Chondro- =
cartilage
- Erythro- = red
blood cell
- Hemangio- =
blood vessels
- Hepato- = liver
- Lipo- = fat
- Lympho- = white
blood cell
- Melano- =
pigment cell
- Myelo- = bone
marrow
- Myo- = muscle
- Osteo- = bone
- Uro- = bladder
- Retino- = eye
- Neuro- = brain
General Symptoms
Some of the following are symptoms that can be associated with cancer.
The acronym, C.A.U.T.I.O.N., can remind us of the most common warning signs of
cancer.
- C - Change in
bowel or bladder habits
- A - A sore that
does not heal
- U - Unusual
bleeding or discharge
- T - Thickening
or lump in the breast or any part of the body
- I - Indigestion
or difficulty swallowing
- O - Obvious
change in a wart or mole
- N - Nagging cough or hoarseness
Sources
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