Americans seem very afraid of cancer, with good reason. Unlike other things that kill us, it often seems to come out of nowhere.

But evidence has increasingly accumulated that cancer may be preventable, too. Unfortunately, this has inflamed as much as it has assuaged people’s fears.

As a physician, I have encountered many people who believe that heart disease, which is the single biggest cause of death among Americans, is largely controllable. After all, if people ate better, were physically active and stopped smoking, then lots of them would get better. This ignores the fact that people can’t change many risk factors of heart disease like age, race and family genetics.

People don’t often seem to feel the same way about cancer. They think it’s out of their control. A study published in Science in January 2015 seemed to support that view. It tried to explain why some tissues lead to cancer more often than others. It found a strong correlation between the number of times a cell divides in the course of a lifetime and the risk of developing cancer.