Cancer is a complicated disease often described by those who know it well in confusing medical, technical, and scientific terms. There's a way to understand it in simple terms, though. And a recent CBS news story features a great run-down on the disease, its causes, how it grows, and more.

Think about this:

• Cancer refers to any one of a large number of diseases characterized by the uncontrollable growth of abnormal cells. These cells have the ability to infiltrate and destroy normal tissue and can spread -- metastasize -- throughout the body.

• Cancer is caused by damage in the DNA. DNA is like a set of instructions for cells and tells cells how to grow and divide. Normal cells can develop mutations in their DNA but can repair most of them. If they cannot make a repair, the cells often die. But certain mutated cells don't repair and don't die. They instead grow and become cancerous.

• Normal, healthy cells grow in an orderly, well-controlled way. They live for a set period of time and then die on schedule. Dead cells are replaced by new normal cells. Cancer cells, in contrast, grow in an uncontrolled manner. They don't die. They 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 cancers form tumors. Leukemia, for example, is a cancer of the blood, bone marrow, lymphatic system, and spleen.
  
  
• Cancer can take decades to develop. By the time a cancerous mass is detected, it's likely that 100 million to one billion cancer cells are present, and the original cancer may have been dividing for five years or more.

• Lung cancer is the top cancer killer among men and women and will kill 160,390 people in 2007.

Researchers have found that when cells become cancerous, they become 100 times more likely to genetically mutate than non-cancerous cells. This explains why tumor cells have so many mutations. Good news on the research front. But bad news on the treatment front -- because therapies that target a certain gene may be largely ineffective in controlling cancer.

"This is very bad news, because it means that cancer cells in a tumor will have mutations that protect them from therapeutics," says lead researcher Dr. Lawrence Loeb, professor of pathology and biochemistry at the University of Washington School of Medicine in Seattle, who presented his findings February 18 at the meeting of the American Association for the Advancement of Science in San Francisco.

Loeb says chemotherapy drugs target specific oncogenes -- genes that affect the malignancy of a cell -- but if cancer cells are mutator cells, then a single tumor may have cells with all sorts of oncogenes. And while chemotherapy may kill some cancerous cells, millions of others will live on.

It's not all bad news, though, says Loeb who believes this research may help doctors determine the stage and malignancy of tumors by testing the number of mutations. It may also help researchers understand what makes a cancer cell a mutator and how to slow the rate of mutation.

"The idea is that if you might normally get exposed to something in the environment at 20 years old that would give you cancer by age 55, then if we cut the mutation rate in half, you might not get cancer until age 90, and you may even die of something else before that," Loeb explained.