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|Cancer: What it is, Causes, Risk Factors, Types and More!|
|Written by Jeff Behar|
Cancer is the general name for a group of more than 100 diseases in which cells in a part of the body begin to grow out of control. Although there are many kinds of cancer, they all start because abnormal cells grow out of control and are able to invade other tissues. Cancer cells can spread to other parts of the body through the blood and lymph systems.
Most cancers are named for the organ or type of cell in which they start - for example, cancer that begins in the colon is called colon cancer; cancer that begins in basal cells of the skin is called basal cell carcinoma.
Cancer types can be grouped into broader categories. The main categories of cancer include:
Today, millions of people are living with cancer or have had cancer. The risk of developing most types of cancer can be reduced by changes in a person's lifestyle, for example, by quitting smoking, limiting time in the sun, being physically active, and eating a better diet.
Half of all men and one-third of all women in the US will
develop cancer during their lifetimes.
Doctors often cannot explain why one person develops cancer and another does not. But research shows that certain risk factors increase the chance that a person will develop cancer. These are the most common risk factors for cancer:
Many of these risk factors can be avoided. Others, such as family history, cannot be avoided. People can help protect themselves by staying away from known risk factors whenever possible.
If you think you may be at risk for cancer, you should discuss this concern with your doctor. You may want to ask about reducing your risk and about a schedule for checkups.
Over time, several factors may act together to cause normal cells to become cancerous. When thinking about your risk of getting cancer, these are some things to keep in mind:
The sections below have more detailed information about the most common risk factors for cancer.Growing Older
The most important risk factor for cancer is growing older. Most cancers occur in people over the age of 65. But people of all ages, including children, can get cancer, too.Family History of Cancer
Most cancers develop because of changes (mutations) in genes. A normal cell may become a cancer cell after a series of gene changes occur. Tobacco use, certain viruses, or other factors in a person's lifestyle or environment can cause such changes in certain types of cells.
Some gene changes that increase the risk of cancer are passed from parent to child. These changes are present at birth in all cells of the body.
It is uncommon for cancer to run in a family. However, certain types of
cancer do occur more often in some families than in the rest of the population. For example,
and cancers of the breast, ovary, prostate, and colon sometimes run in
families. Several cases of the same cancer type in a family may be
linked to inherited gene changes, which may increase the chance of
developing cancers. However, environmental factors may also be
involved. Most of the time, multiple cases of cancer in a family are
just a matter of chance.
People who have a poor diet, do not have enough physical activity,
or are overweight may be at increased risk of several types of cancer.
For example, studies suggest that people whose diet is high in fat have
an increased risk of cancers of the colon, uterus, and prostate. Lack
of physical activity and being overweight are risk factors for cancers
of the breast, colon, esophagus, kidney, and uterus.
Tobacco use is the most preventable cause of death. Each year, more than 180,000 Americans die from cancer that is related to tobacco use.
Using tobacco products or regularly being around tobacco smoke (environmental or secondhand smoke) increases the risk of cancer.
Smokers are more likely than nonsmokers to develop cancer of the lung, larynx (voice box), mouth, esophagus, bladder, kidney, throat, stomach, pancreas, or cervix. They also are more likely to develop acute myeloid leukemia (cancer that starts in blood cells).
People who use smokeless tobacco (snuff or chewing tobacco) are at increased risk of cancer of the mouth.
Ultraviolet (UV) radiation comes from the sun, sunlamps, and tanning booths. It causes early aging of the skin and skin damage that can lead to skin cancer.
Ionizing radiation can cause cell damage that leads to cancer. This kind of radiation comes from rays that enter the Earth's atmosphere from outer space, radioactive fallout, radon gas, x-rays, and other sources.Certain Chemicals and Other Substances
People who have certain jobs (such as painters, construction workers, and those in the chemical industry) have an increased risk of cancer. Many studies have shown that exposure to asbestos, benzene, benzidine, cadmium, nickel, or vinyl chloride in the workplace can cause cancer.Some Viruses and Bacteria
Being infected with certain viruses or bacteria may increase the risk of developing cancer:
Doctors may recommend hormones (estrogen alone or estrogen along with progestin) to help control problems (such as hot flashes, vaginal dryness, and thinning bones) that may occur during menopause. However, studies show that menopausal hormone therapy can cause serious side effects. Hormones may increase the risk of breast cancer, heart attack, stroke, or blood clots.
Having more than two drinks each day for many years may increase the chance of developing cancers of the mouth, throat, esophagus, larynx, liver, and breast. The risk increases with the amount of alcohol that a person drinks. For most of these cancers, the risk is higher for a drinker who uses tobacco.
Cancers that are diagnosed with the greatest frequency in the United States include:
Other types of Cancers
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