7 Big Questions About Cancer, Answered

Every day, billions of cells in our body divide or die off. It’s all part of the intricate processes that keep blood flowing from our heart, food moving through our gut and our skin regenerating. Once in a while, though, something goes awry, and cells that should stop growing or die simply don’t. Left unchecked, those cells can turn into cancer.

The question of when and why, exactly, that happens — and what can be done to stop it — has long stumped cancer scientists and physicians. Despite the unanswered questions that remain, they have made enormous strides in understanding and treating cancer.

“We’re a lot less fearful about telling patients what we do and don’t know, because we know a lot more,” said Dr. George Demetri, senior vice president for experimental therapeutics at Dana-Farber Cancer Institute in Boston.

Here are some of the biggest questions about cancer that scientists have started to answer.

Why do some genetic mutations lead to cancer while others don’t?

Scientists used to think that genetic mutations — changes to the letter sequence of your DNA — were the foundation of all cancers.

They were only partly right. “Mutations are very important — but they’re not the entire explanation for a tumor,” said Douglas Hanahan, a distinguished scholar at the Ludwig Institute for Cancer Research in Lausanne, Switzerland. Some mutations remain dormant our whole lives, never leading to cancer.

It’s now clear that, separate from DNA mutations, there are other factors that alter how genes are expressed. These are called epigenetic changes, and scientists have discovered that they play a huge role in driving cancer.

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