Background on Cancer

Cancer Awareness

Cancer is a group of diseases characterized by uncontrolled growth and spread of abnormal cells, which can result in death.

Cancer is caused by both external factors (tobacco, chemicals, radiation, and infectious organisms) and internal factors (inherited mutations, hormones, immune conditions, and mutations that occur from metabolism). These factors may act together or in sequence to initiate or promote the development of the cancer cells. However, ten or more years can pass between the moment when someone is exposed to external factors and when a test detects cancer in their body.

Can Cancer Be Prevented?

Many cancers cannot be prevented. They are influenced by hormones, genetics or other things that cannot be changed. However, a number of common cancers could be prevented by behavioral changes, such as not smoking or drinking, improving your diet, getting a vaccine, or staying out of the sun.

All cancers caused by cigarette smoking and heavy drinking could be avoided completely. The American Cancer Society estimated that in 2010 about 157,300 cancer deaths are expected to be caused by tobacco use.

In 2009, researchers at the American Institute for Cancer Research discovered that over 100,000 new cancer cases each year are linked to obesity, physical inactivity, and lack of good nutrition. These deaths could also be prevented.

Other cancers are related to infectious agents, such as hepatitis B virus (HBV), human papillomavirus (HPV), human immunodeficiency virus (HIV), Helicobacter pylori (H. pylori) , and others, and could be prevented through behavioral changes, vaccines, or antibiotics.

In addition, many of the more than 68,000 new cases of melanoma in 2010 could have been prevented by protection from the sun’s rays and avoiding indoor tanning.

Even if cancer cannot be warded off entirely, people can take certain precautions, such as regular screening by a health professional, which can find and remove precancerous growths and diagnose cancer at its earliest stages when it is most treatable. Screening can prevent cancers of the cervix, colon, and rectum by allowing removal of precancerous tissue before it becomes malignant. It can also detect cancers of the breast, colon, rectum, cervix, prostate, oral cavity, and skin at early stages, which has been proven to reduce mortality. A heightened awareness of breast changes or skin changes may also result in detection of these tumors at earlier stages.

Cancers that can be prevented or detected earlier by screening account for at least half of all new cancer cases. The five year relative survival rate for these cancers is about 85%, a reflection of real reductions in mortality and earlier diagnosis because of screening.

Who Can Get Cancer?

Anyone can develop cancer but the risk of being diagnosed with cancer increases as individuals age. About 77% of all cancers are diagnosed in persons 55 and older. Cancer researchers use the word “risk” in different ways, most commonly expressing risk as lifetime risk or relative risk.

Lifetime risk refers to the probability that an individual, over the course of a lifetime, will develop or die from cancer. In the US, men have slightly less than a one in two lifetime risk of developing cancer; for women, the risk is a little more than one in three.

Relative risk is a measure of the strength of the relationship between risk factors and a particular cancer. It compares the risk of developing cancer in persons with a certain exposure or trait to the risk in persons who do not have this characteristic. For example, male smokers are about 23 times more likely to develop lung cancer than nonsmokers, so their relative risk is 23. Most relative risks are not this large. For example, women who have a first-degree relative (mother, sister, or daughter) with a history of breast cancer have about twice the risk of developing breast cancer compared to women who do not have a family history.

All cancers involve the malfunction of genes that control cell growth and division. About 5% of all cancers are strongly hereditary, however, most cancers do not result from inherited genes but from damage (mutation) to genes that occurs during one’s lifetime because of either internal or external factors.

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Sources:
World Health Organization (WHO)
Kids Health
International Union Against Cancer
American Cancer Society
Cancer Facts and Figures 2010
Prostate Cancer Foundation