What is Cancer?

For thousands of years, questions about the origins of cancer and how to treat the disease have produced few good answers. A hundred years ago, when radioactivity was discovered, people saw an association between cancer and exposure to X-rays or radioactive elements. More recently, some scientists proposed that cancer was caused by viruses. Others said that cancer arose from inborn genetic flaws. Until recently, there was no unifying theory to tie together these observations. And no matter what the cause, for most of history there was very little that doctors could do to treat cancer effectively.

In the last century there have been moderate improvements in treating cancer, and in the last decade or two researchers have come to a unifying overview of how cancers arise. This unified view assumes that the growth of tissues and the reproduction of cells in our bodies are carefully regulated through the action of key sets of DNA instructions. When those DNA sequences are disrupted--whether through viruses, environmental causes like radiation or toxins, mutations transcription errors or inborn genetic flaws--cell reproduction becomes less well regulated. Eventually, those changes can produce the rapidly reproducing, self-protective and opportunistic cells that typify cancer.


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