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Cancer Risk and Prevention

Common Questions About Causes of Cancer

There are a lot of rumors and myths about cancer that make it hard for people to know what’s true. Here are answers to some of the questions people ask about the causes of cancer.

What is a risk factor?

A risk factor is something that raises the chance of getting a disease. Each cancer has its own risk factors. Having risk factors does not mean that someone will get cancer. Even when a person with a risk factor is found to have cancer, there’s no way to prove that the risk factor caused the cancer.

Some risk factors, like a person’s age or gene damage, can’t be changed. But some risk factors can be controlled. Tobacco use, contact with secondhand smoke, being in the sun, excess body weight, not being active, drinking alcohol, and not eating a healthy diet are risk factors that can be managed. Other risk factors include getting certain viruses and contact with certain kinds of radiation or chemicals.

Can injuries cause cancer?

Falls, bruises, broken bones, or other such injuries do not cause cancer. Sometimes a person might visit a health care provider for an injury and cancer is found. But the injury did not cause the cancer; the cancer was already there.

Can I bring cancer on myself?

Your personality and emotions cannot cause cancer and will not affect the outcome of your cancer. Research shows that there is no connection between personality types or attitude and cancer occurrence or outcomes.

Can stress cause cancer?

Researchers have done many studies to see if there’s a link between personality, attitude, stress, and cancer. It’s known that stress affects the immune system, but so do many other things. At this time, there is no clear evidence that a person's stress level affects their risk of getting cancer.

Does sugar feed cancer?

Sugar intake has not been shown to increase the risk of getting cancer, having cancer spread, or having it get worse. Still, sugars and sugar-sweetened drinks add a lot of calories to the diet and can cause weight gain, which is linked to cancer.

Is cancer contagious?

You can’t catch cancer from someone who has it. You won’t get cancer by being around or touching someone with cancer. When family and friends stay away, people with cancer may feel isolated and alone.  They need your visits and support. To learn more, see Is Cancer Contagious?

Is cancer inherited?

Sometimes, certain types of cancer seem to run in some families. In some cases, this might be because family members share certain behaviors or exposures that increase cancer risk, such as such as smoking. Cancer risk might also be affected by other factors, like obesity, that tend to run in some families.

But in some cases the cancer is caused by an abnormal gene that is being passed along from generation to generation. Although this is often referred to as inherited cancer, what is inherited is the abnormal gene that can lead to cancer, not the cancer itself. To learn more, see Genetics and Cancer.

To learn more

If you want to know more about how cancer starts and spreads, see What Is Cancer? If you have questions that aren’t answered here, please call one of our Cancer Information Specialists at 1-800-227-2345.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.

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Last Revised: November 3, 2020

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