What causes breast cancer?

Cancers have many different causes and sources. One of these sources is a group of chemicals called carcinogens. These carcinogens have been found in industrial pollutants, pesticides, and food additives. People who are exposed to these carcinogens through their occupation or other activities have been known to be more susceptible to cancer. The development of cancer also has been closely linked to heredity. A genetic mutation (a change in the genetic code) could be passed to a child through the sperm or egg. A family history of cancer could be due to a dominant gene that makes cancer more likely to be passed down from generation to generation.

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

(From "Cancer Facts", National Cancer Institute, National Institutes of Health)

What causes oral cancer

Cancer starts when the structure of the DNA (deoxyribonucleic acid) alters - a genetic mutation. DNA provides the cells with a basic set of instructions, much like a computer program for life. The instructions tell cells when to grow, reproduce, and die, among other things. When there is a genetic mutation cells grow in an uncontrollable manner, eventually producing a lump (tumor).

If the cancer is left untreated it grows and eventually spreads to other parts of the body, usually through the lymphatic system - a series of nodes (glands) that exist throughout the body. The lymph glands produce many of the cells of our immune system. As soon as the cancer reaches the lymphatic system it can spread anywhere in the body and invade bones, blood and organs. The cancer cells continue reproducing uncontrollably, gradually occupying more and more space.

Cancer is ultimately the result of cells that uncontrollably grow and do not die. Normal cells in the body follow an orderly path of growth, division, and death. Programmed cell death is called apoptosis, and when this process breaks down, cancer begins to form. Unlike regular cells, cancer cells do not experience programmatic death and instead continue to grow and divide. This leads to a mass of abnormal cells that grows out of control.

With time, oral cancer may spread firstly to other parts of the mouth, then the head and neck, and eventually to other parts of the body. Mouth cancers typically start in the squamous cells (flat, thin cells) than line the lips and the inside of the mouth - they are referred to as squamous cell carcinomas.

Although we know what the risk factors are, experts are not sure what cause the mutations in squamous cells that eventually lead to mouth cancer.