What is a risk factor?

A risk factor is anything that may increase your chance of having a disease. Risk factors for a certain type of cancer might include smoking, diet, family history, or many other things. The exact cause of someone’s cancer may not be known. But risk factors can make it more likely for a person to have cancer.

Things you should know about risk factors for cancer:

• Risk factors can increase a person's risk, but they don't always cause the disease.

• Some people with 1 or more risk factors never develop cancer. Other people with cancer have no known risk factors.

• Some risk factors are very well known. But there's ongoing research about risk factors for many types of cancer.

Some risk factors, such as family history, may not be in your control. But others may be things you can change. Knowing the risk factors can help you make choices that might lower your risk. For instance, if an unhealthy diet is a risk factor, you may choose to eat healthy foods. If excess weight is a risk factor, your healthcare provider may help you lose weight.

The best way you can protect yourself from anal cancer is to be aware of what makes you more likely to get it. Knowing more about the risk factors for anal cancer can help you make healthy choices to help you prevent it.

What are the risk factors for anal cancer?

Human papillomavirus (HPV) infection

HPV infection causes almost all squamous cell anal cancers. It’s the strongest risk factor. HPV is spread through skin-to-skin contact during anal, oral, or vaginal sex. Not having anal sex is the best way to prevent anal HPV infection. Condoms don't totally protect against the virus. That’s because this virus can be spread by skin contact from areas that are not covered by the condom. People may not even know they have HPV. You can have it for years without it causing symptoms.

These factors may put you at higher risk for HPV infection. So they're also linked to higher risk for anal cancer:

• Multiple sex partners. If you've had many sex partners, you’re at higher risk of getting HPV and HIV. Both of these infections are linked to anal cancer. You also have a higher risk if your partner has had many sex partners.

• Anal sex. Having receptive anal sex increases the risk of anal cancer in men and women. Because of this, men who have sex with men are at high risk.

• Weak immune system. You may have a weakened immune system from taking medicines after an organ transplant or if you have HIV.

• Anal warts. Anal warts are caused by HPV. They're a sign that you have or had an HPV infection.

• A history of cervical, vaginal, or vulvar cancer. These cancers are also linked to HPV infection.

Smoking

Smokers are more likely to get anal cancer than nonsmokers. Quitting may reduce the risk for anal cancer and many other types of cancer.

Age

Most cases of anal cancer are found in people ages 50 to 80 years.

What are your risk factors?

Talk with your healthcare provider about your risk factors for anal cancer and what you can do about them.