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The main difference between normal and cancer is one of the growth and differentiation: most cancer cells are in their structure more like those of the young organism (fetus) than those of the adult.
They generally grow and divide more rapidly and in a disorganized fashion, but normal cells only divide and grow until they come into contact with adjacent cells and then stop their growth.
Researchers have tried to treat cancers by using drugs which inhibit the division of cells. The most rapidly dividing cancer cells will be affected by these drugs before the more slowly growing normal cells.
The major problem in cancer research now is concentrated on trying to find out the more delicate difference between cancer and normal cells.
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Researchers have tried to treat cancers by using drugs which _______.