What is Cancer?
The basics on what cancer is.
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All plants and animals, including human beings, are made up of cells. Cells are microscopic bundles of living material,
which are grouped together to form tissues, fluids and organs. Growth, division, death, and replacement of such cells
is a normal process of life.
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Normal cells grow and divide slowly, under very tight control, such that the number of cells in each tissue stays
relatively constant. Cellular growth and division is a key element in healing, for example. Our body responds to a
cut finger, for example, with a series of cellular level activities that produce replacement blood vessel cells and
skin cells, ultimately comprising the healing of that cut.
Cancer is a disease characterized by an abnormal and uncontrolled division of cells, and the tendancy of these cancerous
cells to invade healthy tissues, spreading the disease. Cells that are undergoing this abnormal growth are said to be
malignant. A malignant cell is characterized by failure to respond to the body's signals to stop cellular division,
with a tendency to invade local tissues and to spread to other parts of the body. Cancer begins when a single cell,
or a group of cells, becomes malignnt and starts growing or dividing abnormally fast and out of control. A group or
mass of malignant cells is called a tumor. Cancer that involves only the cells of in the tissue where it began is
referred to as carcinoma in situ. But cancer also commonly spreads to neighboring tissue and other organs. The
invasion healthy tissue by malignant cells may be either directly to adjacent cells, or by traveling through the
bloodstream or lymphatic system to become implanted into other tissues. The transportation of cancerous cells to
non-adjacent tissues is by a process known as metastasis. When a cancer has metastized, it has spread to other parts
of the body. Thus it is possible for bladder cancer cells to be found in other organs, the lungs for example. When
this happens the disease is referred to as metastatic bladder cancer, not lung cancer, even though the lungs are
now involved. Oncologists, physicians who specialize in the study and treatment of cancer, may refer to this new
tumor in the other organ as "distant."
Cancer affects all ages, but the risk of cancer increases with age, and is among the leading causes of death throughout
the world.
Left untreated, this abnormal growth of cells may eventually cause death, often preceeded by periods of illness.
Depending upon the type of cancer and its location in the body, cancer may be treated with surgery, chemotherapy,
or radiotherapy, or by a combination of these methods. Certain drugs and other treatments are known to be effective
in targeting specific forms of cancer, often stopping the abnormal cellular growth or killing off the cancerous cells.
The unregulated growth that characterizes cancerous cells is apparently caused by damage to DNA, resulting in
mutations of the genes that control cell division. These mutations transform a normal cell into a cell that is
malignant. These mutations may be caused by exposure to environmental factors such as tobacco smoke, radioactive
materials, alcohol, by certain viruses that can insert their DNA into the human genome, or exposure to physical
agents called carcinogens. For example, a form of cancer called mesothelioma is known to be caused by exposure to
asbestos.
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What is Cancer?
Types of Cancer
Effects of Nutrition and Diet on Cancer
Effects of Alcohol Consumption on Cancer
Effects of Beta-Carotene on Cancer
Effects of Sexually Transmitted Diseaes and Cervical Cancer
Avoiding Cancer
Skin Cancer
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Ovarian Cancer
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brain Cancer
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Mesothelioma
Multiple Myeloma
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Other Cancer
Articles
Mesothelioma Forms and Symptoms
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