Basic Facts About Cancer: The What, Who, Why, and How

Good News From the American Cancer Society

Thanks to declines in smoking and improved methods for early detection and treatment, more than three-quarters of a million (767,000) cancer deaths have been prevented since the early 1990s. According to the American Cancer Society's Cancer Statistics 2010 report, the cancer death rate among men has dropped by 21 percent since 1991 and by 12 percent for women since 1992.

View more highlights from Cancer Statistics 2010

What is Cancer?

It’s actually a group of diseases that happen when abnormal cells grow uncontrollably. The ability of these abnormal cells to grow out of control and invade other tissues is what makes them cancer cells.

Who’s at Risk?

Unfortunately, anyone can develop cancer. However, the risk increases as we age. Nearly 80 percent of all cancers are diagnosed in people 55 years of age or older.

Why Does Cancer Happen?

The causes are many and varied. A tendency to get cancer can be inherited. Many times, cancer is caused by exposure to environmental factors, like smoking. And, unfortunately, other times, there’s simply no clear cause.

How are the Stages of Cancer Determined?

The stage of a cancer is based on the size of the tumor at the time of diagnosis and the degree to which the disease has spread. Stage I describes a cancer in the early stage, while Stage IV denotes an advanced disease.

The important thing to know is that there are things you can do – like quitting smoking and eating healthy – to reduce the chances of developing cancer. It’s also very important to recognize and watch for some of the general signs and symptoms.

Here are just a few examples:

  • A significant weight loss when you’re not trying to lose weight
  • Extreme tiredness that doesn’t improve with rest
  • Pain or headache that doesn’t go away or respond to treatment
  • Skin changes like darker looking, yellowish, or reddened skin

Of course, there are also other symptoms commonly associated with specific cancers, such as long-term constipation or diarrhea (colon cancer), sores that do not heal or new skin changes (skin cancer), or a cough that doesn’t go away (lung cancer).

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