When you hear the word "cancer", chances are that you think of it as a single disease, like "pneumonia" or "AIDs". But this is somewhat misleading.
Cancer is the name we give to any illness that results when our body's own cells grow out of control.
Grow out of control. That's the key distinction.
All cells grow. That is what they are intended to do. Cell growth occurs naturally billions and billions of times each day in our bodies. You cut your finger. Some cells die. The cut heals. Some cells grow. You brush your hair. Old hair, made up of dead cells, falls out. New hair grows in from the roots. You age. Some brain cells die. You learn. Some brain cells are born.
Billions and billions of these cell transactions go on everyday without us noticing them. Cells are created from the division of other cells. They do what they are supposed to do--carry blood, help us grow new hair, mend a cut finger --then they take a bow, exit the stage and die, only to be replaced instantaneaously by the new kids on the block.
We humans are forever renewing ourselves. The skin you have covering your body has been sloughed off and rebuilt many times since you were a baby. Your head of hair is not the same head of hair you had as an infant.There are many processes that control a cell’s growth and division, each of which can go wrong. As a general rule-of-thumb, several of these control mechanisms need to be damaged before a cell becomes cancerous.
There are between 50 and 75 trillion cells in the human body. That's "trillion", with a "t". A trillion is 1000 billion. 1 million million. A lot. So, when we say that cells are dividing billions and billions of times each day we are not exaggerating.
So, what is cancer? Cancer-- out of control growth-- occurs when one --just one --of those 50 trillion cells goes wacky. It comes on stage, does its job, but when it is time to exit and die, it doesn't leave. It hangs on, and keeps on growing and growing. Article Continues Below.
Cancer is a collection of over 200 diseases in which cells of an organ or tissue in the body become abnormal, growing and multiplying out of control. Normal cells have a life cycle and they reproduce themselves throughout the body in an orderly and controlled manner. Normal growth continues throughout life to replace worn out tissue, to heal wounds, and to maintain healthy organs. When cells grow out of control, they usually form a mass, called a tumour.
Some tumours grow and enlarge only at the site where they begin and these are referred to as benign tumours. Other tumours not only enlarge locally but also have the potential to invade and destroy the normal tissue around them and to spread to distant parts of the body. Such tumours are called malignant tumours or cancers.
Distant spread of a cancer occurs when malignant cells become detached from the original (primary) tumour, get carried to other parts of the body and establish themselves in the new site as an independent (secondary) cancer. A tumour that has spread in this manner is said to have metastasized and the secondary tumour (or tumours) is called a metastasis (or metastases).
Cancer is an equal-opportunity disease. It afflicts the poor and the rich, the old and the young. Several Us Presidents have had cancer. Here is a list:
Abraham Lincoln had cancer in office Ulysses Grant died of throat cancer, but not in office. Grover Cleveland had jaw cancer in office. Herbert Hoover had intestinal cancer, but not in office. Franklin Roosevelt, possibly had melanoma while in office, still disputed. Dwight Eisenhower had melanoma, but not in office. Ronald Reagan colon cancer, colonic polyps, and skin cancer while in office. Bill Clinton had basal cell carcinoma while in office.