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.

Overview

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. Because cancer cells continue to grow and divide, they are different from normal cells. Instead of dying, cancer cells outlive normal cells and keep forming new abnormal cells. Another difference between cancer cells and normal cells is that cancer cells can invade (grow into) other tissues.

Cells become cancer cells because of damage to DNA. Most of the time, when DNA gets damaged the cell can fix it. But if the cell can’t repair the damage, the cell dies. In cancer cells, the damaged DNA is not repaired and the cell doesn’t die like it should. Instead, this cell goes on making new cells even though the body does not need them. These new cells will all have the same DNA damage as the first cell does. In most cases the cancer cells form a tumor. Some cancers, like leukemia, do not form tumors. Instead, these cancer cells involve the blood and circulate through other tissues where they grow. But sometimes the extra cells in these blood cancers may also form a mass of tissue called a tumor.

While people can inherit damaged DNA, DNA damage is generally caused by something we are exposed to in our environment. Sometimes the cause of the DNA damage is something obvious, like cigarette smoking, asbestos, even the sun. Staying away from things that are known to damage DNA (like smoking) as a part of a healthy life style lowers the chance that more DNA damage will take place. This can reduce the risk of cancer -- even in people who have an inherited tendency to get cancer.

Cancer types can be grouped into broader categories. The main categories of cancer include:

• Carcinoma - cancer that begins in the skin or in tissues that line or cover internal organs
• Sarcoma - cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue
• Leukemia - cancer that starts in blood-forming tissue such as the bone marrow and causes large numbers of abnormal blood cells to be produced and enter the blood
• Lymphoma and myeloma - cancers that begin in the cells of the immune system
• Central nervous system cancers - cancers that begin in the tissues of the brain and spinal cord

For more information on types of cancer and definitions of cancer terms, click here to go to the National Cancer Institute dictionary.

Outlook

The outlook for cures for most cancers are clearly through early detection. It is very clearly testing and screening that dramatically improves the chance of being diagnosed early.  Early diagnosis - and family support - may give you the upper hand on a cure.

Testing / Screening

As there are many different kinds of cancers, there are also many different types of tests to screen for them.  The following is the most common forms of testing for each of the following types of cancer:

• Prostate Cancer - PSA testing (done through blood testing) is still the most common test although it can sometimes show false positive results
• Colorectal Cancer - fecal blood tests and colonoscopy are the most common tests available
• Breast Cancer - self-examination and mammograms are the generally used
• Cervical Cancer - PAP test is the most common test
• Testicular Cancer - self-examination, beta HCG and alpha-fetoprotein testing (done through blood testing) and ultra-sound tests are commonly used
• Lung Cancer -X-ray & biopsy are most commonly used, although new blood tests, breath tests and urine tests are in development
• Oral Cancer - dentists usually are first to diagnose through mouth & saliva testing.  No simple tests that are effective exist.
• Pancreatic Cancer - no early detection tests exist although tests for patients with advanced cases are available
• Skin Cancer - skin screening exam which highlights abnormal skin cells

If you want more information, an excellent resource is the American Cancer Society (click this link to visit) or the National Cancer Institute (click this link to visit) from which the information above has been extracted.