Cancer Resources

What Is Cancer?

According to the Mayo Clinic, cancer refers to any one of a large number of diseases characterized by the development of abnormal cells that divide uncontrollably and have the ability to infiltrate and destroy normal body tissue. Cancer can spread throughout your body.

What Causes Cancer?

Cancer begins with damage (mutations) in your DNA. Your DNA is like a set of instructions for your cells, telling them how to grow and divide. Normal cells often develop mutations in their DNA, but they have the ability to repair most of these mutations. Or, if they can't make the repairs, the cells often die. However, certain mutations aren't repaired, causing the cells to grow and become cancerous. Mutations also cause cancer cells to live beyond a normal cell life span. This causes the cancerous cells to accumulate.

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According to the American Cancer Society, lung cancer remains the top cancer killer among both men and women, the report shows. Around 160,390 deaths are expected in 2007. About 213,380 people are expected to develop lung cancer. Incidence and death rates among women have flattened in recent years, but fewer men are getting lung cancer or dying from it.

How Does Cancer Grow?

According to the Mayo Clinic, normal, healthy cells in your body grow in a very orderly and well-controlled way, living for a set period of time and then dying on schedule. When a normal cell dies, your body replaces it with another normal cell. Cancer cells grow in an uncontrolled manner. They forget to die and therefore the diseased cells accumulate. One malignant cell becomes two, two become four, four become eight, and so on, until a mass of cells (a tumor) is created. Tumors remain small until they're able to attract their own blood supply, which allows them to obtain the oxygen and nutrients they need to grow larger.

Not all tumors are cancerous, and not all cancers form tumors. For example, leukemia is a cancer that involves blood, bone marrow, the lymphatic system and the spleen, but doesn't form a single mass or tumor.
Cancer can also spread (metastasize) and invade healthy tissue in other areas of your body.

Cancer can take decades to develop. By the time a cancerous mass is detected, it's likely that 100 million to 1 billion cancer cells are present, and the original cancer may have been dividing for five years or more.

To Learn More About Cancer:

• The American Cancer Society has more information.

• The Cancer Treatment Centers Of America has information about treatment options.

• For alternative treatment options, go to National Center for Complementary And Alternative Medicine.

• Read "My Cancer", a daily account of one person's fight for cancer.

• Click here to read more statistics about the number of cancer cases and deaths.

• You can read more about the different types of cancers and how to treat them through a CBSNews.com interactive.

• Although new treatments are constantly being tested, there are six methods that are commonly used for cancer treatment, according to the National Cancer Institute. You can read more about them here.

• You can search for a clinical trial through the National Cancer Institute by clicking here.