Cancer: A Genetic Disease
With cancer, a person may inherit a predisposition that helps set the process off, but it can take decades — even a lifetime — to accumulate the additional mutations needed to establish a tumor. That is why, scientists say, cancer usually strikes older people and requires an element of bad luck.
“You have to get mutations in the wrong place at the wrong time,” Druker says.
Other genetic diseases may involve one or two genetic changes. In cancer, scores of genes are mutated or duplicated and huge chunks of genetic material are rearranged. With cancer cells, said Dr. William Hahn, an assistant professor of medicine at Harvard Medical School, “it looks like someone has thrown a bomb in the nucleus.”
In other genetic diseases, gene alterations disable cells. In cancer, genetic changes give cells a sort of superpower.
At first, as scientists grew to appreciate the complexity of cancer genetics, they despaired. “If there are 100 genetic abnormalities, that’s 100 things you need to fix to cure cancer,” said Dr. Todd Golub, the director of the Cancer Program at the Broad Institute of Harvard and MIT in Cambridge, Mass., and an oncologist at the Dana-Farber Cancer Institute in Boston. “That’s a horrifying thought.”
Making matters more complicated, scientists discovered that the genetic changes in one patient’s tumor were different from those in another patient with the same cancer. That led to new questioning. Was every patient going to be a unique case? Would researchers need to discover new drugs for every single patient?
“People said, ‘It’s hopelessly intractable and too complicated a problem to ever figure out,’ ” Golub recalled.
But to their amazement, scientists are finding that untangling the genetics of cancer is not impossible. In fact, they say, what looked like an impenetrable shield protecting cancer cells turns out to be flimsy. And those seemingly impervious cancer cells, Golub said, “are very much poised to die.”